KR101476075B1 - Facilitating transport mode input/output operations between a channel subsystem and input/output devices - Google Patents

Abstract

Sending, by the channel subsystem, a process login (PRLI) request message to the control unit indicating whether the channel subsystem supports bidirectional data transmission; Receiving from the control unit a PRLI response message indicating whether the control unit supports bi-directional data transmission; Collecting a plurality of commands, at least one of which specifies an input data transfer and at least one specifies an output data transfer; Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And receiving at least one input data message including input data to be stored in the main storage of the host computer system from the control unit.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method, apparatus, and computer program product for facilitating transport mode input / output operations between a channel subsystem and input / output devices.

The present invention relates generally to input / output (I / O) processing and, more particularly, to providing features for facilitating transport mode I / O operations.

Input / output (I / O) operations are used to transfer data between the memory and the I / O devices of the I / O processing system. More specifically, by executing I / O operations, data is written to one or more I / O devices from memory and data is read from memory into one or more I / O devices (read).

To facilitate processing of I / O operations, the I / O subsystem of the I / O processing system is employed. The I / O subsystem is coupled to the I / O devices of the main memory and the I / O processing system to direct the flow of information between the memory and the I / O devices. One example of an I / O subsystem is a channel subsystem. The channel subsystem uses channel paths as a communication medium. Each channel path includes a channel coupled to a control unit, which is further coupled to one or more I / O devices.

A channel subsystem and an I / O device are coupled to a transport mode (a transport) that supports the transfer of one or more command control blocks to transfer data between I / mode. The transport control word (TCW) specifies one or more I / O commands to be executed. For commands that initiate certain I / O operations, the TCW may include memory areas associated with the operation, actions to take each time a transfer is completed from the memory area or memory area, and other options Specify.

Such an I / O operation system typically involves the handling of individual operations as input data operations (e.g., read operations) or output data operations (e.g., write operations). These systems do not typically support bi-directional operations, and in particular do not include the ability to generate or transmit indications of bi-directional support.

One embodiment includes a computer program product for performing I / O operations initiated by input / output (I / O) operation instructions in a host computer system configured for communication with a control unit. The computer program product comprising a storage medium of the type readable by a processing circuit and for storing instructions for execution by the processing circuit for processing a method comprising the steps of: tangible storage medium, the method comprising: sending a process login (PRLI) request message to the control unit to initialize a link between the channel subsystem in the host computer system and the control unit, Sending by the subsystem, the PRLI request message comprising one field, the field having a value indicating whether the channel subsystem supports bi-directional data transmission; Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission; Providing an indication to the host operating system that bi-directional data transfer is supported; and in response to executing the I / O operation command received from the host computer system, performing one method . The method includes gathering a plurality of commands associated with the I / O operation command received from the host computer system, the at least one of the plurality of commands specifying input data transmission and the plurality of commands At least one of which specifies output data transmission; Transferring the plurality of commands to the control unit; Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And receiving from the control unit at least one input data message comprising input data to be stored in the main storage of the host computer system, wherein the input data message associated with at least one of the plurality of commands comprises: Explicitly stated.

Another embodiment includes an apparatus for performing an I / O operation initiated by an input / output (I / O) operation command in a host computer system configured for communication with a control unit. Wherein the host computer system is configured to: send a process login (PRLI) request message to the control unit to initiate a link between the channel subsystem in the host computer system and the control unit, The PRLI request message comprising one field, the field having a value indicating whether the channel subsystem supports bi-directional data transmission; Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission; Providing an indication to the host operating system that bi-directional data transfer is supported; and in response to executing the I / O operation command received from the host computer system, performing one method The method comprising: collecting a plurality of commands associated with the I / O operation command received from the host computer system, the at least one of the plurality of commands specifying an input data transfer Wherein at least one of the plurality of commands specifies output data transmission; Transferring the plurality of commands to the control unit; Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And receiving from the control unit at least one input data message comprising input data to be stored in the main storage of the host computer system, wherein the input data message associated with at least one of the plurality of commands comprises: Explicitly stated.

Another embodiment includes a method of performing an I / O operation initiated by an input / output (I / O) operation command in a host computer system configured for communication with a control unit. The method comprising the steps of: transmitting, by the channel subsystem, a process login (PRLI) request message to the control unit to initiate a link between the channel subsystem in the host computer system and the control unit, sending the PRLI request message comprises a field, the field having a value indicating whether the channel subsystem supports bidirectional data transmission; Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission; Providing an indication to the host operating system that bi-directional data transfer is supported; and in response to executing the I / O operation command received from the host computer system, performing one method The method comprising: collecting a plurality of commands associated with the I / O operation command received from the host computer system, at least one of the plurality of commands specifying input data transfer and the plurality At least one of the commands specifying the output data transmission; Transferring the plurality of commands to the control unit; Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And receiving from the control unit at least one input data message comprising input data to be stored in the main storage of the host computer system, wherein the input data message associated with at least one of the plurality of commands comprises: Explicitly stated.

Additional features and advantages are realized through the techniques of the embodiments of the present invention. Other embodiments and features are considered to be part of the claimed and claimed invention herein. For a better understanding of the present invention with the advantages and features, reference is made to the following detailed description and drawings.

The subject matter regarded as the invention is particularly pointed out and particularly pointed out in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the present invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings.
Figure 1 illustrates one embodiment of an I / O processing system that combines and uses one or more embodiments of the present invention;
Figure 2 shows one embodiment of a transport control word (TCW);
Figure 3 shows an embodiment of a transport command control block (TCCB);
Fig. 4 shows an embodiment of a transport command information unit (IU) including the TCCB of Fig. 3;
Figure 5 shows an embodiment of the transport command header of the transport command IU of Figure 4;
Figure 6 shows an embodiment of the Transport Command Area Header (TCAH) of the TCCB of Figure 4;
Figure 7 shows an embodiment of the Transport Command Area (TCA) of the TCCB of Figure 4;
8 is a table describing exemplary decisions of various data counts for one-way data transfer operations;
Figure 9 is a table describing exemplary decisions of various data counts for bidirectional data transfer operations;
Figure 10 shows an embodiment of a device command word (DCW);
Figure 11 illustrates one embodiment of a control flags field of the DCW of Figure 10;
Figure 12 illustrates one embodiment of a transport command area extension (TCAX);
Figure 13 illustrates one embodiment of a CBC-offset block;
14 is a flow chart illustrating one embodiment of a method of performing a transport mode I / O operation;
Figure 15 illustrates embodiments of transport-data IUs used to transport input and output data between a channel and a control unit and / or an I / O device;
Figure 16 shows an embodiment of a transport response IU;
Figure 17 shows an embodiment of a status area of the transport response IU of Figure 16;
Figure 18 shows the components of an exemplary process login (PRLI) request;
Figure 19 shows the components of an exemplary PRLI response;
20 shows an exemplary channel path description block provided from the channel subsystem to the host computer system OS.
FIG. 21 shows exemplary channel description data of the description block of FIG. 20, including channel subsystem capability data.

Embodiments of the present invention facilitate input / output (I / O) processing in a computer system. In one embodiment, transport commands are provided for managing I / O operations and the transfer of data over a channel path. The transport commands transfer transport command meta-information (TCMI), which is used to manage data transfer checking and transmission of additional DCWs. A TCMI is defined in one or more data transport information units (IUs) for defining, specifying and verifying information about data to be transmitted in an I / O operation. The transport commands may include an interrogate command, a transport -CBC-offset block (TCOB) command, and a transport-TCA-extension (TTE) command.

In one embodiment, the I / O processing is facilitated by enabling the host computer to increase the number of commands that can be sent to the device for I / O operations. For example, a TCMI in the form of a Transport Command Area Extension (TCAX) may be sent from the host to the device to increase the number of commands that may be associated with I / O operations. In one embodiment, the TCAX is transmitted via a device command word (DCW), also referred to as a Transfer TCA Extension (TTE), and the DCW includes a Transport Command Area As well as commands to be executed.

I / O processing may also be facilitated by providing a means for the I / O device to continue I / O operation when encountering an incorrect length record. For example, a DCW-incorrect-length facility can be installed in a host system and a control unit or device. This facility is provided for inaccurate length (IL) checking that can be performed by the control unit. A press-incorrect-length or SLI field (a suppress-incorrect-length or SLI field) may be added to the DCW sent to the device. When this bit is activated, DCW chaining is allowed to continue when an incorrect length condition is detected by the control unit.

The I / O processing may also be facilitated by providing a means to transmit both the read and write commands to the device in a single I / O operation. Prior art TCW channel programs specify all write commands or all read commands. The bidirectional operation may be accomplished by setting one or more flags in the command IU's transport command header (TCH), for example, by setting both the read and write flags all to one and providing both the read and write data counts, Can be specified. Also, flags in an initiation or login message, such as a Process Login (PRLI) request message, may be set to indicate that the channel subsystem supports bidirectional data transmission. A response message, such as a PRLI accept message, may include a flag that may be set to indicate whether the device supports bidirectional data transmission. If bidirectional data transfer is supported by both the host and the control unit, the device does not report an error even if both the read and write flags are set in the command IU. This capability is an improvement over the prior art Fiber Channel protocols, which do not support bidirectional data transfer operations. As described herein, "bidirectional data transmissions" refers to transmissions of all input and output data performed within a single TCW I / O operation, for example, both read and write commands within a single TCW I / O operation And executes it.

1 is a block diagram of an I / O system including a host computer system 102 including a data storage and / or processing system such as a zSeries® mainframe computer manufactured by International Business Machines Corporation (IBM®). O processing system 100 of the present invention. IBM is a registered trademark of International Business Machines Corporation, A-mone, New York, USA. Other product names used herein may also be registered trademarks, trademarks or product names of International Business Machines Corporation or other companies. The host computer system 102 includes various processing, storage, and communication elements. In one embodiment, the host computer system 102 includes memory components, such as one or more central processing units (CPUs) 104, main storage or memory 106, an extended storage or memory 108, And one or more operating systems (OSs) 110 executed by one or more CPUs 104. For example, one CPU 104 may run a Linux® operating system 110 and / or z / OS® operating system 110 as other virtual machine instances . The CPU 104 is the control center of the I / O processing system 100. CPU 104 includes sequencing and processing facilities for instruction execution, interruption actions, timing functions, initial program loading, and other machine-related functions. The CPU 104 is coupled to the main memory 106 and / or the expanded memory 108 via a connection 113, such as a bi-directional or one-way bus.

The host computer system 102 also includes a host system 101 and a plurality of I / O devices 116, which may be controlled by one or more control units 118, System 114. < / RTI > I / O devices include devices such as printers, self-tape units, direct access-storage devices, displays, keyboards, communication controllers, teleprocessing devices, and sensor-based equipment. In this detailed description, the terms "control unit" and "device" may be used interchangeably, or the control unit may be considered to include one or more devices. The channel subsystem 114 directs the flow of information between the I / O devices 116 and the host computer system 102. It relieves the CPU 104 of the burden of directly communicating with the I / O devices and allows the data processing to proceed concurrently with the I / O processing. The channel subsystem 114 is coupled to the CPUs 104, main memory 106, and / or the expanded memory 108 via a connection 120 such as a bus.

In one embodiment, the channel subsystem 114 includes a respective "channel path" 122 that connects the channel subsystem 114 to each control unit 118 via a connection 124, such as a serial or parallel link, 0.0 > I / O < / RTI > The control units 118 may be connected to the channel subsystem 114 via one or more channel paths 122 and the I / O device 116 may include one or more control units 118 and / And may be connected to the I / O device 116. In all cases, one individual I / O device 116 may be made accessible by multiple channel paths. The channel path may use various types of connections, for example, a parallel interface, a serial-I / O interface, and a FICON I / O interface. For example, the serial channel path may include one or more optical fibers coupled to the control unit 118 through a dynamic switch 126 in, for example, a fiber channel fabric, The parallel interface may include a plurality of electrical or optical fiber conductors.

In one embodiment, the channel subsystem 114 includes one or more individual channels 128, each of which may be coupled to one or more of the control units 118 via one or more channel paths 122, 0.0 > and / or < / RTI > I / O devices 116. Each channel 128 includes processing electronics such as a local channel microprocessor 130 and a local channel memory 132 that is coupled to and accessible by the local channel microprocessor 130. The local channel memory 132 includes a channel-program designation, a channel-path identifier, a device number, a device count, such as status indications, as well as information about path availability and functions pending or being performed.

One or more sub-channels are also located within each channel 128. Each subchannel is a data structure located in channel memory 132 that provides information about its associated I / O device 116 and its attachement to the channel subsystem 114. The subchannel also provides information about I / O operations and other functions involving the associated I / O device 116. [ The subchannel is a means by which the channel subsystem 114 provides information about the associated I / O devices 116 to the CPUs 104. [ In one embodiment, the number of sub-channels provided by the channel subsystem is independent of the number of channel paths 122 for the associated I / O devices 116. For example, a device 116 that is accessible via alternate channel paths 122 is still represented by a single sub-channel.

Each control unit 118 provides logic for operating and controlling one or more of the I / O devices 116, and through the use of common facilities, each I / O device 116 to the link interface provided by the channel 128. < RTI ID = 0.0 > The common facilities include indications of the execution of I / O operations, the status of the I / O devices 116 and the control unit 118, the control of the timing of data transfers through the channel path 122, / O Provides for specific levels of device control. The control unit 118 may be installed separately or may be physically and logically integrated into the I / O device, the channel subsystem, or the CPU.

One or more of the components of the I / O processing system 100 are described in detail in the publication number " z / Architecture Principles of Operation ", published in August 2010, Publication No. SA22-7832-08, ). ≪ / RTI >

I / O operations are described as all operations related to data transfer between the host computer system 102 and the I / O devices 116. As described herein, I / O operations include communication between the channel subsystem 114 and the device 116 (in one embodiment, through the control unit 118) (E.g., a channel command word or CCW), a single command message (e.g., a transport command information unit or a transport command control block (TCCB)) containing multiple commands, or multiple chained commands , Multiple CCWs) are transmitted from the channel subsystem 114 to the device. The I / O operations may also include one or more response messages generated by the device 116 or the associated control unit 118 in response to receiving and / or executing commands or chained commands.

In one embodiment, the I / O operations are initiated at the device 116 by execution of I / O commands generated by the OS 110 specifying a subchannel associated with the device 116. To request the channel subsystem 114 to perform various functions of the I / O operation, such instructions are executed by the CPU 104 in the host system, which is executed by sending parameters to the channel 128 or subchannel .

For example, by sending parameters to the target subchannel, which requires the channel subsystem 114 to perform a start function on the I / O device 116 associated with the subchannel, START SUBCHANNEL "command. The channel subsystem 114 performs a start function to locate the channel path to the device 116 and to perform an I / O operation once the channel path is selected, including the START SUBCHANNEL command Including information transmitted during execution, using information in the subchannel.

When a command such as a START SUBCHANNEL command is executed by the CPU 104, the channel 128 starts performing an I / O operation. In one embodiment, a High Performance FICON (HPF) protocol for communication between the channel subsystem 114 and the devices 116 and / or the control units 118, The channel subsystem 114 operates. FICON and HPF are described in detail in "Fiber Channel: Single-Byte Command Code Sets Mapping Protocol-4 (FC-SB-4) FC-SB-4)) ", T11 Project 2122-D, Rev. 3.00.

In one embodiment, execution of the START SUBCHANNEL command sends the contents of the operation request block (ORB) to the channel subsystem 114. The ORB specifies a channel program that contains the addresses of one or more command words (e.g., channel command words or transport command words, which are discussed further below). There are two modes of subchannel operation. In one embodiment, the host computer system 102 operates in a command mode and specifies the command word (s) in the form of a channel command word (CCW). In another embodiment, the host computer system operates in a transport mode and specifies the command word (s) in the form of a transport command word (TCW).

The subchannel can enter the transport mode when the FCX (Fiber Channel extensions) facility is installed and the start function is set to the subchannel as a result of the execution of the START SUBCHANNEL command specifying the TCW channel program. The subchannels remain in the transport mode until the start function is reset in the subchannel. In all other cases, the subchannel is in command mode.

In command mode, the channel executes a CCW channel program that contains a single channel-command word or a sequence of sequentially-executed channel-command words and controls a specific sequence of channel operations. The control unit performs the CCW I / O operation by doing so by decoding, accepting, and executing the CCW commands by the I / O device. The one or more CCWs configured for sequential execution form a CCW channel program and are each executed as one or more I / O operations.

The Fiber-Channel Extensions (FCX) facility is an optional facility, which is a transport mode consisting of a transport-command-control block (TCCB) and a transport-control word (TCW) And is provided for the formation of channel programs. The TCCB includes a Transport-Command Area (TCA), which holds a list of one or more (for example up to 30) I / O commands in the form of device-command words (DCWs). The TCW and its TCCB can specify a read or write operation. In one embodiment, the FCX-bidirectional-data-transmission facility can be installed in a system that supports transport mode operations, which means that if the connected device 116 and the control unit 118 support bidirectional- Allowing computer system 102 to specify transmission of both input and output data within a single transport mode I / O operation. When the control unit 118 recognizes bi-directional data transmissions, the TCW and its TCCB may specify both read and write data transfers, depending on the device.

In the transport mode, a single transport command word (TCW) specifies the in-memory location of the TCCB (and also the location in memory 106 or 108 of one or more data areas) It is sent as a single message instead of CCWs. The control unit 118 performs the transport mode I / O operation by doing so by decoding, receiving, and executing the TCCB and the individual DCWs contained therein. If the ORB specifies a TCW channel program, the channel subsystem 114 uses the information in the TCW designated to transmit the TCCB to the control unit 118. The contents of the TCCB are ignored by the channel subsystem 114 only after the TCCB is transferred to the control unit 118 and has meaning to the control unit 118 and the associated I /

In one exemplary embodiment, the control unit 118 generates a response message in response to executing the channel program. The control unit 118 may also generate a response message without executing the channel program under a limited number of communication scenarios, for example, in order to notify the channel subsystem 114 that the channel program is not to be executed . The control unit 118 may include a number of elements to support communication between the I / O communication adapter and the I / O devices, as well as to support channel program execution. For example, the control unit 118 may analyze (parse) messages as well as one or more queues, timers, and registers to facilitate communication and status monitoring, ) Processing logic.

2 illustrates an embodiment of a transport-control word (TCW), which is stored in a host system (e.g., main memory 106) and transmitted from a channel 128 to a control unit 118 At least one control block is specified. In one embodiment, the control block is a transport-command-control block (TCCB), and the contents of the TCCB are transported to the control unit 118 and the I / O device 116 for processing. When the TCW 140 specifies a TCCB, the TCCB includes a TCA, which specifies one or more device-command words (DCWs) and associated choices. For DCW that specifies a command to initiate data transfer (other than control data held within the TCCB), the TCW 140 specifies one or more storage areas where the data is to be located.

In one embodiment, the TCA includes a transmit TCA extension (TTE) command, which is provided to transmit additional DCWs and / or control data in addition to those that can be accommodated in the TCCB. The TTE may send a TCA extension (TCAX) to the control unit (which includes at least one DCW), for example, by chaining the last DCW of the TCCB to the first DCW of the TTE, It is considered to be a logical extension.

Referring again to FIG. 2, the embodiment of TCW 140 is a 64-byte control block designated at a 64-byte boundary. The TCW includes various fields as described below.

For example, a number of flag fields 142 indicate whether direct or indirect data addressing is used to look for input data, output data, or TCCB. The output transport-indirect-data addressing (TIDA) field indicates whether the output data is directly or indirectly addressed. For example, when word 0, bit 7 of TCW 140 is zero and output data is specified, output-data-address field 144 specifies the location of the output data in absolute storage do. When bit 7 is one, the output-data-address field 144 stores the output storage location or locations as the TIDA word (TIDAW) in the list of TIDAWs (TIDAL) or the absolute address of the first TIDAW . The input TIDA field indicates whether the input data is directly or indirectly addressed. For example, when word 0, bit 5 is zero and the input data is specified, the input-data-address field 146 specifies the input storage location, i.e., the absolute address of the location where the input data is to be stored. When bit 5 is one, the input-data-address field 146 specifies the absolute address of the TIDAW or first TIDAW in the TIDAL designating the input storage location or locations. The Transport-Command-Control-Block TIDA (TCCB-TIDA) field indicates whether the TCCB is addressed directly or indirectly. For example, when word 0, bit 6 is zero, the TCCB-address field 148 specifies the absolute address of the TCCB for the TCW, and when bit 6 is one, the TCCB- (148) specifies the absolute address of the TIDAW or TIDAL specifying the location or locations of the TCCB.

TCW 140 also includes a Transport-Command-Control-Block Length (TCCBL) field 150 that specifies the length within the bytes of the TCCB. For example, the TCCBL field contains an unsigned integer that can be used to determine the number of TCCBs (for example, when added to 20 for one-way data transmissions or to 24 for two-way data transmission) Specifies the length in bytes.

When displaying the number of bytes to be transferred to the main memory 106, the read operations R field 152 is non-zero (e.g., bit 14 of word 1 is one ). Write operations (W) field 154 is non-zero (e.g., bit 15 of word 1 is one) when indicating the number of bytes to be transferred from main storage. If both R-field 152 and W-field 154 are 1, a program-check condition is acknowledged, unless target device 116 and control unit 118 support bi-directional data transmission (recognized). If the W-bit is 1 and the TCW is interrogated TCW, then the program-check condition is acknowledged.

The output-to-data address field 144 indicates the location in the storage of all output data to be sent to the device. For example, when bit 15 (W-field bit 154) of word 1 is 1 and bit 7 of flags field 142 (output-TIDA flag) is 0, words 2-3 are stored in 64- Specifies the bit output position. When the W-bit is 1 and the output-TIDA flag is 1, words 2-3 specify the 64-bit position in the absolute storage of the list of TIDAWs or TIDAWs that specify the location or locations of the output storage. The input-data address field 146 indicates the location where the input data will be stored when received from the device. For example, when bit 14 (R-field bit 152) of word 1 is 1 and bit 5 (input-TIA flag) of flags field 142 is 0, words 4-5 are stored in 64- Specifies the bit input position. When the R-bit is 1 and the input-TIDA flag is 1, words 4-5 specify the absolute storage location of the list of TIDAWs or TIDAWs that specify the input storage location (s).

The transport-state-block address 156 specifies the location in the storage of the transport-state block for the TCW. For example, words 6-7 specify the 64-bit location in the absolute storage of the transport-state block for the TCW.

The Transport-Command-Control-Block Address field 148 specifies one or more (direct or indirect) addresses of the TCCB. For example, if the TCCB-TIDA bit (bit 6 of the flags field) is 0, then words 8-9 specify the 64-bit location in the absolute storage of the TCCB. When TCCB-TIDA is zero, the TCCB is specified to reside in a contiguous area of the storage. If the Transport-Command-Control-Block-TIDA bit is 1, words 8-9 specify the 64-bit location in the absolute storage of the list of TIDAWs or TIDAWs that specify the location in the absolute storage of the TCCB. When the TCCB-TIDA bit is 1, the TCCB is specified to reside in noncontiguous areas of the storage.

The output count field 158 specifies the number of output bytes of the TCW. For example, when bit 15 (W-bit) of word 1 is 1, word 10 holds the unsigned integer total count of TCW output bytes. The input-count field 160 specifies the number of input bytes of the TCW. For example, when bit 14 (R-bit) of word 1 is 1, word 11 holds the unsigned integer total count of the input bytes of the TCW.

If the TCW specifies an interrogation operation, the query-TCW address field 162 indicates the location in the storage of the query TCW. For example, when the START SUBCHANNEL command specifies TCW, word 15 of the TCW is not checked. However, when the CANCEL SUBCHANNEL command is a start pending and not a status pending subchannel for the TCW channel program, bits 1-31 of word 15 of the TCW designated by START SUBCHANNEL are set to the sub- Specifies the 31-bit position in absolute storage of the query-TCW used to initiate the query operation for the channel. If word 15 holds 0s when CANCEL SUBCHANNEL is issued, the query operation is not started. When CANCEL SUBCHANNEL is issued, bit 0 of word 15 must be 0; otherwise, the program-check condition is recognized as an interrogate-failed status indicated. When CANCEL SUBCHANNEL is issued and bits 1-31 of word 15 do not hold zeros, bits 1-31 of word 15 must specify the storage location in the 64-byte range, otherwise the program- It is recognized as an interrogate-failed status indicated. Word 14 may be reserved to extend the query-TCW-address field to 64 bits.

3 and 4, the transport-command-control block (TCCB) 170 includes one or more separate commands as part of the TCW I / O operation, To the control unit 118 and / or the device 116. The TCCB 170 relieves the channel from having to transmit multiple messages or information units and also transfers the responsibility for performing the operation to the control unit and then transmits the control unit 118 Eliminates the need to send a response for each command. Instead, the control unit 118 can execute all commands and send a response when the operation is complete.

The TCCB 170 may be variable in length, may hold header and trailer information, and may include one or more (e.g., 1 to 30) , Chained) device-command words (DCWs), so that they can be executed by the control unit 118 in an a sequential manner. The TCCB 170 may reside as a plurality of blocks of storage resident or non-contiguous as a single block of contiguous storage. For example, the TCCB-TIDA flag in TCW 140 described above is used to specify whether the TCCB resides in contiguous storage.

Examples of TCCB are shown in Figures 3 and 4. As shown in Figure 4, the TCCB 170 is a part of a transport command information unit (IU) 172 that is transmitted to the control unit 118 to initiate an I / (118). In one embodiment, the transport command IU 172 comprises an 8-byte SB-4 header 174, a next 4-byte transport command header (TCH) 176, and a TCCB 170. The TCCB 170 includes a 16-byte transport-command-area header (TCAH) 178, a variable length transport-command area (TCA) 180, and a transport command area trailer (TCAT) do. Byte bi-directional read data-transfer length (BRDL) field 184 for bi-directional operations, and the 4-byte LRC field 184, Field 188. < / RTI > These fields will be further described below.

Referring to FIG. 4, the SB-4 header 174 provides FC-4 addressing information to identify the logical path and device 116 for data transmission. The SB-4 header 174 provides information including the channel ID and the control unit ID for the logical path between the channel 128 and the control unit 118 as well as the device ID.

5, the TCH 176 includes information regarding the TCCB 170 and related device operations. In one embodiment, the TCH 176 holds 4 bytes and is located immediately after the SB-4 header 174 in the transport command IU 172. The TCH 176 includes fields such as a length field ("L1") 190, a lead field ("R") 192, and a light field ("W" The Ll field (e.g., located in bits 24-29) is used to indicate the length of the 1-word LRC field 184 immediately following TCA 180 plus TCA 180 in words, Specify. For example, if the control units 118 do not support bidirectional operations, then the total amount of data transferred in the transport command IU 172 is the L1 field plus 8 (i.e., L1 field plus two-word SB-4 header, 1-word TCH, 4-word TCAH and 1-word DL); Otherwise, the control unit recognizes the transport-command IU integrity error due to the data count error. When the control units support bidirectional operations, the total amount of data to be transferred in the transport-command IU 172 is L1 field plus 8 (i.e. L1 field plus two-word SB-4 header, one-word TCH, Word TCBL and 1-word DL for bidirectional operation) or L1 field plus 9 (i.e. L1 field plus 2-word SB-4 header, 1-word TCH, 4-word TCAH, ); Otherwise, the control unit will recognize the transport-command IU integrity error due to the data count error. If the transport-command IU integrity error is not acknowledged, the LRC location in the TCCB may be determined based on the LI field and an LRC check may be performed.

The Read (R) field 192 specifies that the TCA 190 includes one or more leads or input commands. 5, the R field 192 is an R bit, bit 30, which, when set to 1, indicates that the TCA 180 holds one or more commands to transmit read data . When the R bit is set to 0, the TCA 180 does not hold any commands to transmit the read data. When the R bit is 1 and the W bit (for example, bit 31) is 0, the operation is referred to as a read operation. When both the R and W bits are set to zero, the TCA 180 does not hold any commands to transmit read or write data, indicating that the I / O operation is not performing data transfer . When both the R and W bits are set, the TCA 180 may hold commands to transmit both read and write data, where the operation is referred to as bidirectional operation. If the bidirectional operation is specified but the control unit 118 does not support bidirectional operations or if the control unit 118 supports bidirectional operations but the transport-command IU 172 does not have the BRDL field 188, The control unit 116 or the control unit 118 recognizes a TCH content error due to a read-write conflict. When the R bit is 0 and the control unit 118 or the device 116 encounters a command in the TCA 180 that is attempting to transmit the leaddata, the TCCB content error is recognized due to an invalid lead attempt.

The Write (W) field 194 specifies that the TCA 180 includes one or more write or output commands. In one embodiment of FIG. 5, the W field is a W bit, bit 31, indicating that when TCA 180 is set to 1, it holds one or more commands to transmit write data . When this bit is set to zero, the TCA 180 does not hold any commands to transmit the write data. When the W bit is 1 and the R bit (i.e., bit 30) is 0, the operation is referred to as a write operation. When the W bit is 0 and the control unit 118 or device 116 encounters a command in the TCA specifying a write command, a TCCB content error is recognized due to an invalid write condition.

6, one embodiment of the TCA header (TCAH) 178 includes information about the TCA 180 and the operations described therein, such as TCA length and device indications . In this embodiment, byte 3 of word 1 is the "L2" length field 196, which includes TCA 180 plus the words 2 and 3 of the TCA header plus a 4-byte LRC field 184 (TCA 180) Followed by an unsigned binary integer that specifies, in bytes, the length of the length of the next byte. The service-action code field 198 (e.g., bytes 0-1 of word 2) contains an unsigned integer value specifying the type of operation specified by the TCCB. For example, a hex value '1FFE' indicates the SB-4 device I / O operation and a hex value '1FFF' indicates the SB-4 device support functions. The priority number field 200 (i.e., byte 3 of word 2) contains a control unit I / O priority number.

Referring to FIG. 7, the transport-command area (TCA) 180 is a variable length area, which is used to transmit one or more (eg, 1 to 30) commands to device- Quot;) < / RTI > The length of TCA 180 is, in one embodiment, the integral number of 4-byte words. For DCWs 202 that specify device control data, TCA 180 also holds control data associated with each DCW 202. Each DCW 202 that specifies control data reduces the maximum DCW capacity by one or more DCWs, depending on the size of the command-related data. For DCWs 202 specifying input or output data, the TCW 140 specifies the associated storage area or areas and the DCW specifies a count of bytes to transfer. In one embodiment, the maximum size of the TCA is 240 bytes. 7, when there is sufficient space in the TCA 180 for the entire DCW 202, the DCW 202 may control the previous DCW 202 or the control associated with the previous DCW 202, It starts on the word boundary after the data. When the last DCW 202 in the TCA 180 specifies control data that is not the true number of words, the subsequent LRC field 184 begins at the word range that comes after the control data.

For some devices, the list of DCWs 202 may extend beyond the fit in range of the TCA 180. [ In such cases, a TCA extension (TCAX) field containing additional DCWs may be specified and transmitted as if TCAX is the output data (e.g., may be sent as part of an output transport-data IU) . However, TCAX is treated as a logical continuation of TCA 180 rather than as transmission data. TCAX is specified in TCA 180 by a transport-TCA-extension (TTE) DCW. TCAX and TTE DCW will be described in more detail below, and an embodiment of TCAX is shown in Figures 12 and 13.

As shown in FIGS. 3 and 4, the TCCB may include a transport-command-area trailer (TCAT) 182, which provides additional information about the TCCB, including various count information. In one embodiment, when one-way data transmission is specified (R bit or W bit set to 1) or no data transmission is specified (both R and W bits in TCW are set to 0), TCAT 182) are two words in length. When bidirectional data transmission is specified (both the R and W bits in the TCW are set to 1), the TCAT 182 is three words in length.

For example, when one-way data transfer is specified, the transport count or data length (DL) field 186 specifies a 32-bit unsigned integer count (the "transport count value") of the total data to be transferred. When the read operation is specified (TCW R-bit is 1), the value of the transport-count field in TCAT can be determined by summing the count field values in the DCWs 202, each of which specifies a read-type command. The sum is rounded up to the nearest multiple of 4 and the rounded sum is increased by 4 to reach the transport count value. When the read operation is specified, the transport count value should be the same as the value in the TCW input-count field 160, rounded to the next multiple of 4, plus 4.

When the write operation is specified (the W bit in the TCW is 1), the count field values in the DCWs 202 specifying the write command are summed. In addition, the count field values in all the transport-command DCWs (described in more detail below) that specify the transmission of the transport command-meta information, plus the size of the reserved fields in the plus TCMI, are added to the sum. (Note that the size of the TCMI Reserved field may be zero). The sum of counts of all TIDAW-specified control block checks (CBC) or cyclic redundancy check (CRC) bytes and padding bytes is added to the sum. The sum is rounded to the nearest multiple of 4, and the rounded sum is increased by 4 to a transport-count value. When a write operation is specified, the transport count value should be equal to the value in the TCW output-count field 158, rounded to the next multiple of 4, plus 4. When neither the read nor write operation is specified (both the W and R bits in TCW are 0), the transport count value must be zero.

When bidirectional data transmission is specified, the DL field 186 is a write count and specifies a 32-bit unsigned integer count of the total output data to be transmitted. The transport count value of the DL field (write-count field) in the TCAT 182 is determined for the write operation as described above. The bi-directional read data length (BRDL) field 188 specifies a 32-bit unsigned integer count of the total input data to be transmitted. The transport count value for the BRDL field 188 is determined for the read operation as described above.

In one embodiment, for a write operation or a bidirectional operation, the DL field holds a 4-byte unsigned binary integer, which specifies the number of bytes to be sent by the channel to the control unit for its operation, And last pad and CRC bytes, and if the COB is included in the first transport-data IU of the write operation, it also includes the COB, all COB pad bytes and COB CRC bytes. If the TTE DCW is present in the TCA, the DL field also contains TCAX, all TCAX pad bytes and TCAX CRC bytes.

Figures 8 and 9 are tables summarizing the determination of TCW input-count, output-count, and TCAT transport count values for one-way and two-way transmissions, respectively.

For bidirectional operation, the Bidirectional-Read-Data-Length (BRDL) field contains a 4-byte unsigned binary integer that specifies the number of bytes to be sent by the control unit to the channel for its operation, Contains all pad bytes required to round to the word range, if not already in the word range plus 4 bytes for CRC. For operations other than bidirectional operations, the device will recognize the TCH content error due to a read-write conflict if the transport-command IU has a BRDL field.

Referring to FIG. 10, a device-command word (DCW) 202 specifies a command to be executed. For commands that initiate certain I / O operations, it specifies a count of the bytes on which the operation is performed, an action to take each time the transfer is completed from storage or from storage, and other selections. The storage area or areas associated with the DCW data-transfer operation may be stored in the input-data-address field 146 of the TCW 140 that specifies the TCCB 170 including the DCW 202, according to the operation specified by the command. Or by an output-data-address field 144. Whether the input-data-address field 146 or the output-data-address field 144 specifies storage directly or indirectly is specified by the input-TIDA and output-TIDA flags in the TCW 140.

In one embodiment, DCW 202 is an 8-byte control block designated on a word boundary in TCW 140. The DCW 202 includes fields such as a command code field 204, control flags field 206, a control data count 208 and a DCW data count 210.

The command code field 204 (e.g., bits 0-7 of word 0) specifies the operation to be performed. Whether the command is valid depends on the device and on the value of the service-action code field 198 in the TCAH 178. The basic commands include read, write, control, sense and transport. The channel subsystem 114 distinguishes between the following operations: control, output forward (write), input forward (read, sense, sense ID), input backward read backward), branching (transfer in channel), and transport. Some commands, when executed, cause the device to chain and start execution of the next command, but not all of the conditions for command chaining are met, although this does not result in the transfer of data. Each of the basic operations will be described below.

The read command initiates the execution of a device operation to perform device-to-channel data transfer. The write command initiates execution of a device operation to perform channel-to-device data transfer. The control command starts execution of the device operation using the control data provided in the DCW. A sense command is similar to a read command except that the data is obtained from sense indicators rather than from a record source. Control commands and associated control data are provided for management of specific I / O devices and control of the device during execution of I / O commands. The transport command is provided to manage the transmission of data through the I / O operation and channel path, and is not device specific. Such commands manage the transport of control block checking data, such as cyclic redundancy check (CRC) data, and the transport of additional DCWs in transport-data IUs.

The control-data (CD) count field 208 specifies the number of control data bytes associated with the DCW 202. For example, byte 3 of word 0 specifies the length of the control data, in bytes. If the command code specifies a command that requires control data, and if byte 0 of word 0 specifies fewer control-data counts than required for that command, a unit-check condition or TCCB content error is acknowledged. If the command code specifies a command that requires control data and byte 3 of word 0 holds 0 or past the end of the TCA (past the end of the specified TCAX) If so, a device-detected-program check condition or TCCB content error is acknowledged.

The DCW data count field 210 specifies a byte count of data (e.g., data to be transferred for a read or write operation, i.e., customer data) designated by the TCW for the current DCW 202. For example, the DCW data count is included in word 1 of DCW 202 of FIG. 10 and specifies a 32-bit unsigned integer count of the bytes in the storage area designated by TCW for this DCW. The DCW data count field 210 indicates the number of bytes to be transferred between the channel and the control unit during the execution of the DCW, which does not include any pads or CRC bytes.

Referring to FIG. 11, in one embodiment, the DCW 202 includes various control flags 206. The chain-command (CC) flag 212 specifies the intention to perform chaining of commands. Chaining of commands causes the next DCW 202 in the TCA 180 to execute after the current device operation is normally completed and the device is aware of the end of the device. The CC flag 212 is set to zero in the final DCW in the TCA. In the embodiment of FIG. 10, bit 9 (CC bit) of word 0 specifies chaining of the commands when it is one. 1, that bit causes the operation specified by the next DCW to be initiated after the normal completion of the current DCW. When the control-data count is zero, the next DCW comes immediately after the DCW in the TCA or within TCAX. When the control-data count is non-zero, the next DCW comes immediately after the control-data, rounded to a word boundary, specified for that DCW. When the chain-command flag is 1, in one embodiment, the next DCW position in the TCA or TCAX is determined by adding 8 to the current DCW position and the value in the CD count field and rounding it up to the nearest word range do. If the chain-command flag is 1 in the DCW in the TCA, the next DCW position passes the end of the TCA (past), and TCAX is specified, the next DCW is placed at the beginning of the specified TCAX.

The control flags field, in one embodiment, includes a press length indicator (SLI) field 214. When a DCW-incorrect-length facility is supported by the channel 128 and the control unit 118, a bit (e.g., bit 2) is provided in the SLI flag field 214, Length-to-length condition and an incorrect-length condition is detected by the control unit 118-controls whether the length is to be displayed in the transport-response IU by the control unit. If the DCW data count does not match the amount of data requested by the device for the write DCW or if the DCW data count does not match the amount of data available in the device for the read DCW, . When DCW-incorrect-length facility is not supported by channel 128 and control unit 118, bit 2 is reserved and set to 0 by the channel and ignored by the control unit. When the SLI flag 214 is 1 and an incorrect-length condition exists for the current DCW, command chaining, if indicated, will be allowed and the control unit will continue to execute the next DCW. If the SLI flag is 0 and an incorrect-length condition exists for the DCW, the command chaining is not allowed, even if it is displayed, and the control unit 118 aborts the I / O operation. When an incorrect-length condition exists for the DCW 202 and the SLI flag 214 in the DCW is set to 1, the data transfer is performed as described below, otherwise the operation is terminated and an abnormal termination condition Will be reported for its operation.

For the lead DCW 202, if the DCW data count is greater than the amount of data available at the device 116 for that command, the following applies. If CC flag 212 is 1 (chaining is indicated), the data available at device 116 is sent to channel 128 and pad bytes (set to 0) are also sent to DCW 202 The amount of transmitted data becomes equal to the DCW data count. All transmitted data, including pad bytes, are included in all calculations of the CRC required for its operation. If the CC flag 212 is 0 (no chaining has been indicated), the data available at the device is sent to the channel and no further data is transmitted or pad bytes (set to 0) are sent to the DCW 202 ) Is equal to the DCW data count. All pad bytes plus transmitted data will be included in the CRC calculation required for operation. Whether the pad bytes will be transmitted for this case will be determined by the model. If the DCW data count is less than the amount of data available on the device for the command, only an equal amount of data, such as the DCW data count, is sent to the channel 128 for the DCW 202. Only the transmitted data will be included in the calculation of the CRC required for operation.

For the write DCW 202, if the DCW data count is greater than the amount of data requested by the device for the command, the following applies. If the CC flag 212 is 1 (chaining is indicated), the amount of data specified by the DCW data count will be transferred to the control unit 118. The transmitted data will be used to calculate all the CRCs required for operation, and data not required by the device 116 is discarded. If the CC flag is 0 (chaining is not indicated), the amount of data requested by the device 116 is transferred to the control unit 118. Additional data is transmitted until the next intermediate CRC word or until the data count for DCW is exhausted. All transmitted data is used in the calculation of all CRCs required for operation. If the DCW data count is less than the amount of data requested by the device 116 for the command, the amount of data specified by the DCW data counter is transferred to the control unit 118. The transmitted data is used in the calculation of all CRCs required for operation.

The transport-command DCW does not specify a specific data transfer command (i.e., the customer data requested to be transmitted by the host computer command), but explicitly specifies a transport command to perform the support function associated with the transport-mode I / O operation Is a type of DCW. The transport-command DCW can specify the control data and also specify the transport of the transport-command-meta information (TCMI). The TCMI includes information about the transfer functions in I / O operations, such as the status of I / O operations at the device, additional DCWs that are not suitable for or can be accommodated by the TCCB, And data used to control control block checking (CBC) information, such as cyclic redundancy check (CRC) data.

When the transport-command DCW specifies the transmission of the TCMI to the device, the TCMI is transmitted as output data (ie, to the transport-data IU). The size of the TCMI depends on the command, for example, a multiple of four. When the size of the TCMI is an even multiple of 4, the TCMI can be extended by four reserved bytes, the TIDAWs are used to specify the output storage areas, and the Insert-CBC flag holds the TCMI Is 1 in the last TIDAW used to specify the storage, the chain-command bit is 1 in the transport command DCW specifying TCMI, and the subsequent DCW specifies the transmission of TCMI or output data. When the transport command specifies a transmission to the TCMI device and all of the above conditions are met and the TCMI is extended by four reserved bytes, the four reserved bytes are included in the data-count in the transport command DCW Count value in the last TIDAW used to specify the storage that holds the TCMI, the output-count value in the TCW, and the transport-count value in the associated TCCB (for one-way data transfers) Note that this is included in the light-count value within the associated TCCB.

In one embodiment, the TCMI includes query information (via query DCW), CBC-offset block (via transmit-CBBC offset block DCW), and TCA extension (via transmit-TCA extended DCW).

Figure 12 shows a transport-command (TTA) command, called a transport TCA extension (TTE) command, specifying the TCA extension (TCAX) 220 contained in the TCA 180 of the TCCB 170 and to be transmitted to the control unit 118 RTI ID = 0.0 > DCW < / RTI > TCAX is considered to be a logical extension of TCA 180. For some devices 116, the list of DCWs 202 associated with the I / O operation exceeds the number of DCWs that can be accommodated in the TCA 180. In such a case, the TTE DCW may be included at the end of the TCW 140, specifying the TCAX 220 to be transmitted as output data (e.g., to the data-to-transport IU). The content of the TTE DCW may include a command code that includes a transmit-TCA extension command (e.g., a value of 50 hex).

For example, the TCA 180 is variable in length, the maximum size is 240, and the DCW is 8 bytes. Thus, in this example, a maximum of 30 DCWs may be transmitted in the TCCB 170. [ However, for DCWs 202 specifying control commands that require control data, the control data immediately follows each DCW 202 in the TCCB. Thus, the TCCBs 170 holding such commands are limited to less than 30 DCWs. The TTE DCW may be used to specify additional DCWs required for I / O operations not conforming to the TCA 180.

As shown in FIG. 12, the TCA extension (TCAX) is a variable-length area, which is a logical continuation of the other transport-command IU or TCA 180 in the TCCB and contains a list of DCWs and associated control data. TCAX maintains one or more additional DCWs (in addition to those sent in the initial TCCB) and associated control data for TCW I / O operations, and to extend the list of DCWs required for I / O operation May be transmitted in another TCCB or transport-data IU. In one embodiment, the length of the TCAX is an integral multiple of four.

As shown in FIG. 12, in one embodiment, TCAX 220 includes control data for DCW 202 and / or previous DCW 202. When the last information in TCAX 220 is DCW 202, the end of DCW 202 defines the end of meaningful information in TCAX 220. The end of the control data defines the end of meaningful information in TCAX 220 when the final information in TCAX 220 is control data and the control data ends in a 4-byte range. When the final information in the TCAX 220 is control data and the control data does not end in the 4-byte range, padding bytes are added to the control data to reach the 4-byte range and the end of the padding bytes is stored in the TCAX (220) Defines the end of meaningful information. When the size of the meaningful information in the TCAX 220 divided by 4 is an odd number, there are no reserved bytes; Otherwise, the four bytes immediately following the meaningful information in TCAX 220 are reserved and hold zeros. When the control data for the final DCW 202 in the TCA 180 is held in the TCAX 220, the control data is the first data in the TCAX 220. Additional DCWs and control data within the TCAX 220 are processed as defined for the TCA 180.

In one embodiment, when the TCOB DCW (described in detail below) is not present in the TCA 180, the TTE DCW is the first DCW 202 in the TCA 180. When the TCOB DCW is present in the TCA 180, the TTE DCW is the second DCW 202 in the TCA 180. The TTE DCW data count specifies the length of TCAX (220) and can be a quadruple of 4 bytes. TTE DCW control - The data count is 0 and the chain command flag in the TTE DCW is set to 1. TTE DCW data does not include TCAX CRC or TCAX pad bytes.

The TTE command (TTE DCW) must be sent to the device indicating the support for the TTE command and the control data for the final DCW in the TCA should be sent to the device that has the TCA length of a certain maximum (e.g., 60 words) Bytes, or when the TCA length is greater than, for example, 58 words and one or more additional DCWs are required for I / O operation. When the COB is provided in the light transport-data IU, TCAX comes after the COB CRC. When COB is not provided, TCAX will be sent to the first write transport-data IU of I / O operation.

Another type of DCW is the transmit CBC-offset block (TCOB) DCW, which is the command to send the CBC offset block (COB) to the control unit. CBC data is called control block checking data, which is used to verify that the correct amount of input or output data is being transferred in I / O operation. In one embodiment, the CBC is cyclic redundancy check (CRC) data, the COB is a CRC offset block, and the TCOB DCW is a transmit CRC-offset block DCW. Generally, the cyclic redundancy check (CRC) is an error-detection code, which is configured to detect accidental changes to raw data transmitted between the channel 128 and the control unit 118 do. A CRC-enabled device (e.g., channel 128) computes and appends a short, fixed-length binary sequence to each block of data to be transmitted or stored, Or "CRC word ". For example, when CRC generation is provided, channel 128 generates a CRC on the transmitted data and inserts the calculated value at the end of the last data byte. When a CRC word is received or read, the receiving device (e.g., control unit 118) may compare its check value with a freshly calculated value from that data block, Perform a CRC and compare the resulting check value with an expected residue constant. If the check values do not match, the block holds an error in the transmitted data. Even if CBC data is described in the embodiments herein, it is not so limited.

As shown in FIG. 13, the COB 222 specifies the location of the intermediate CRC words (e.g., in the transport-data IU) within the transport data for read or write data transmission. In one embodiment, the COB is provided when the first DCW 202 in the TCA 180 holds the TCOB command, i.e., when it is the TCOB DCW. The intermediate CRC offsets are CRC words located between data in the data transmission IU and before the end of the IU. The COB 222 holds a list of 1-word values, referred to as CRC offsets 224, each of which identifies the byte offset of each intermediate CRC word in the transport data. For example, the COB is a variable-length control block, which contains a list of 4-byte entries, each of which identifies the offset of the CRC specified by the TIDAW to be inserted in the output data.

In the embodiment shown in FIG. 13, the COB 222 includes 1 to N + 1 words (1 to N + 1 words) (CRC offset words 224) of the intermediate-CRC offsets. If a COB 222 is provided in the transport-data IU, the COB may also include 0 words or 1 word of pad bytes and 1 word of CRC. The pad bytes may be provided such that the word holding the CRC is in the word range as long as it is not a double word range. The final word of the COB will hold the intermediate CRC offsets from 0 to N and, if present, a CRC covering the pad words. If the COB is provided as control data for the TCOB DCW, there will be no COB padding or CRC and the control-data count will be equal to four times the number of intermediate-CRC-offset fields in the COB.

For write operations, the TCOB DCW specifies that the COB is transported to the device 116. The TCOB DCW command code includes, for example, a TCOB command which is a value of 60 hex. The position of the COB may be determined by the control-data count and provided as control data to the first write transport-data IU of the I / O operation or to the TCOB DCW of the I / O operation. For example, when the CD count of the TCOB DCW is not zero, the COB 222 immediately follows the TCOB DCW in the TCA 180 and the CD count specifies the number of CRC offsets in the COB multiplied by four. When the CD count is zero, the COB 222 is specified as the TCMI sent with the output data, and the location of the COB is specified by the output-data-address field 144 in the TCW 140.

Each intermediate-CRC offset in the COB 222 indicates a relative offset, in bytes, from the first byte of data in the transport-data IU. If the COB 222 is provided in the transport-data IU, then the first byte of data for the write transmission is the first byte following the COB CRC if TCAX 220 is not provided, or TCAX if TCAX is provided It is the first byte following the CRC. If the COB is provided to the TCA 180 as DCW control data, the first byte of data for the write transmission is either the first byte in the transport-data IU or the TCAX 220 if the TCAX 220 is not provided It is the first byte following the TCAX CRC, if provided. When provided to the transport-data IU, the COB is provided to the first write transport-data IU of the I / O operation.

Another type of transport-command DCW is an interrogated DCW, which is used to determine the state of the TCW I / O operation at the device 116. [ The query command does not initiate operation at device 116 nor does it affect the state of device 116 nor reset the associated allegiances and associated logical paths associated with device 116. The example query DCW contains a query command code (e.g., holds a value of 40 hex). If there are exceptions in the command code, the SLI flag, count and CD-count fields, all other fields in the DCW hold 0, otherwise holds the device-detected program-check condition. If the CD count of the query DCW is greater than zero, the query data is specified.

A query operation is performed on the device 116 with the logical path having the TCW I / O operation in progress to obtain information about the state of operation at the device 116. [ In one embodiment, TCCB 170 for query operation includes a single DCW with query device command code (e.g., X'40). The TCAH 178 for the query operation may hold R bits set to 1 to specify the read data transfer for that operation. The query operation is recognized in the control unit 118 when the control unit 118 receives the transport-command IU specifying the query command. When the query operation is recognized in the control unit 118 and the control unit 118 can successfully execute the query command, the control unit 118 can provide the status in the transport-response IU, An interrogate extended status describing the state of the query, and a device address specified by the query transport-command IU.

Referring to FIG. 14, a method of performing a transport mode I / O operation 300 is illustrated. The method includes one or more steps 301-305. In one embodiment, the method includes executing steps 301-305 in the order described. However, certain steps may be omitted, steps added, or the order of the steps changed.

If the host computer (e.g., OS 110) executes an instruction (e.g., a START SUBCHANNEL) at step 301, it indicates that the channel subsystem 114, specifying the TCW 140, So that the ORB is transmitted. In one embodiment, capturing the status to determine whether to transport the TCCB 170 to the I / O device 116 and transferring the specified TCCB 170 to the I / Program-check conditions associated with the validity of the TCW fields are checked by the channel subsystem 114. If such a program-check condition exists, the TCCB 170 is not transported and its program-check condition is recognized. For example, the TCCB-address field 148 is checked to see if it specifies an available storage location. If the TCCB flag is 1, then the TCCB-address field 148 is also checked to determine whether it specifies an address in the quadword range. Additional program check conditions are described in further detail below.

At step 302, the channel 128 selects a transport-command IU containing control blocks and associated control information for the TCW 140, such as a transport-command-control block (TCCB) TCW I / O operation is initiated (e.g., via control unit 118) to the I / O device when transmitting to device 116. [ Information (e.g., commands, input data, and output data) associated with the execution of I / O operations and device operations may be transferred between the information units IUs . In one embodiment, the IUs are in the form of SB-4 information units (IUs).

In one embodiment, IUs or other messages are transmitted between the channel and the control unit via one or more exchanges. An exchange pair consisting of two one-way exchanges is used to transmit the IUs by the channel 128 and the other is used by the control unit 118 to transmit the IUs, -4 Link - Required for all SB-4 device-level functions to be executed for control functions and in command mode. A single bidirectional exchange is called a transport exchange and is used for device-level functions that are performed in transport mode. IUs transmitted by channel 128 during the execution of the SB-4 link-control function or while executing the SB-4 device-level function in command mode are restricted to one exchange and during that operation, IUs are limited to other exchanges. The exchange in which the channel 128 transmits IUs is called an outbound exchange and the exchange in which the channel 128 receives IUs is called an inbound exchange. When both the outbound exchange and the inbound exchange for the execution of the same link-level or device-level function exist between the channel 128 and the control unit 118 at the same time, (128). A channel program running on a single connection uses only one exchange pair. If the connection is removed by closing exchanges during the channel program, a new exchange pair is created to complete the channel program. The channel 128 may initiate the exchange pair by sending the IU (or Initiation IU) that opens the new exchange as an uncolicited command or as a voluntary control information category. The control unit 118 may initiate the exchange pair by sending an initiation IU as a voluntary control or spontaneous data information category.

IUs transmitted by the channel and the control unit during the execution of I / O operations performed in transport mode are limited to single, duplex exchanges, called transport exchanges. Channel 128 can open the transport exchange by sending the transport-command IU as a voluntary command category (initiating IU). The channel 128 may open multiple transport exchanges, each of which may do so for the other device 116 or for the same device 116 on other logical paths. A new transport exchange can be opened for a specific device on a logical path, which can be done when there is already a transport exchange for the device and the logical path to perform the query operation; If not, the channel 128 waits for the existing transport exchange or exchange pair to be closed before initiating a new transport exchange for the device on the logical path.

At step 303 the control unit 118 receives the TCCB 170 and the transport-command IU 172 and accepts the TCCB 170 if certain conditions are met. . When the transport-command IU 172 is received, the TCCB 170 is considered current in the control unit 118 until the execution of the TCCB 170 in the control unit 118 is deemed complete . If the transport-command IU 172 is not accepted because of an error condition, the transport-response IU is returned to the channel 128 and an initial status flag is set to 1, ) Indicates that an error has occurred before starting execution of TCCB 170. [ The control unit 118 may provide error information to the status field and the I / O extended status fields in the transport-response IU (described below), which is to identify the transport-command IU error . In one embodiment, the exemplary conditions described below must be satisfied in order for the transport-command IU 172 to be accepted at the control unit 118:

1) the transport-command IU meets the following integrity checks;

a) For control units that do not support bidirectional operations, the L1 field plus 8 in the TCH shall specify the amount of data, such as the amount of data received by the control unit for the transport-command IU, Because of the error, a transport-command IU integrity error will be acknowledged;

b) For control units that support bidirectional operations, the L1 field plus 8 or 9 in the TCH must specify the amount of data, such as the amount of data received by the control unit for the transport-command IU, Because of the counter error, the transport-command IU integrity error will be recognized; And

c) The LRC field in the TCCB will be valid, otherwise a transport-command IU integrity error will be acknowledged due to an invalid LRC error

2) The specified logical path will be set, otherwise a logical-path-not-established error will be recognized;

3) For commands that require the device to be installed and ready, the device address will be set to the installed and ready device, otherwise an address-exception condition will be recognized;

4) If the bidirectional data transmission is not supported by the control unit or if the transport-command IU does not have a BRDL field, then the R and W bits will not all be set to 1 within the TCH; Otherwise a TCH content error will be recognized;

5) The TCCB in the Transport-Command IU will meet all of the following conditions, otherwise a TCCB content error will be recognized:

a) The L2 field shall specify a length that is exactly 8 bytes greater than the L1 field, and shall hold a value of at least 20 bytes and not exceeding 252 bytes;

b) byte 1 of word 0 of TCAH will be 0;

c) The format control field in TCAH will be the same as hex'7F ';

d) The service-action code in the TCAH will hold a valid value

e) If the R and W bits are all set to zero, the data-length (DL) field will be zero; And

6) If another TCW I / O operation is in progress for the logical path and device address specified in the transport-command IU, then the service-action code specifies hex'IFFF 'and the command code in the first DCW of the TCA queries Will specify the command code, otherwise a non-interrogate-second-operation error will be recognized.

In one embodiment, the channel 128 assumes that a connection exists when the transport-command IU 172 is transmitted and the control unit 118 determines that the connection is established when the transport-command IU 172 is received It is considered to exist. Thus, channel 128 can be used to determine whether control unit 118 has accepted TCCB 170, or until device 116 has received the TCCB 170, until the I / O operation is terminated by the control unit 118 to the transport- I do not know about the progress of I / O operation. In one embodiment, the channel 128 may set a time window to receive a response from the control unit so that if the channel does not receive a transport-response IU in its window, Recognizes a transport command timeout

At step 304, when the TCCB 170 is received, the control unit 118 processes the TCA 180 and executes each DCW 202. When the DCW 202 is selected by the I / O device 116 for execution and the first DCW of the transport mode program (i.e., the first DCW in the TCCB) or during command chaining, the subsequent DCW 202 When the control of the I / O operation is taken over, the DCW 202 is in the current state. The first DCW to be implemented may be considered to be located at offset 0 of the TCA 180 in the TCCB 170. [ Each additional DCW in the channel program is located within the TCA 180 (or within the TCAX 220) and is used when the DCW is needed by the I / O device 116.

The command chaining is controlled by the DCW chain command (CC) flag in the DCW. This flag specifies the action to be taken in response to the exhaustion of the current DCW. Chaining occurs between successive DCWs in the TCA. When TCAX is specified, chaining also occurs between the final DCW in TCA and the first DCW in TCAX, and between successive DCWs in TCAX. When the current DCW specifies command chaining and no abnormal conditions are detected during operation, the completion of the current DCW causes the next DCW to be the current DCW and to be executed by the device. If TCAX is specified and the offset of the next DCW passes past the end of the TCA, the chaining continues at the first DCW of TCAX and the TCAX offset is determined by subtracting the TCA length from the calculated offset. Thus, command chaining proceeds in ascending order of TCA offsets, and then TCAX offsets in ascending order when TCAX is specified. If a condition occurs (such as an attention, unit check, unit exception, or incorrect length) (unless the SLI field 214 in the DCW is activated), the order of operations is complete and the state associated with the current operation is Causing an interruption condition to be generated. In this case, the new DCW is not executed.

The data requested to be transmitted via the I / O operation is transmitted between the channel 128 and the control 118 via one or more transport-data IUs during the processing of the DCWs 202 in the TCCB 170. [ The read operation performs only the read data transfer, the write operation performs only the write data transfer, and the bidirectional operation can perform both the read and write data transfer.

15, channel 128 transmits one or more transport-data IUs 310 to control unit 118 for write or bidirectional operation, which may include write data 312 for that operation ). For read or bidirectional operation, the control unit 118 transmits at least one transport-data IU 314 on channel 128 for transmitting the specified lead data 316 for its operation. Pad bytes 318 are used to pad the data area into the next word range when the CRC is included in the last word of the data area for which the CRC is calculated and the data area to be covered is not an integral number of data words. This applies to data areas to be covered by COB, intermediate and final CRC. The value used for the pad byte depends on the model.

The final CRC field 320 indicates that the transport-data IU 310, 314 is the last transport-data IU transmitted by the channel 128 or control unit 118 for TCW I / IUs 310 and 314, respectively. In one embodiment, the last-CRC field 320 includes a word-aligned 32-bit redundancy-check code. For read or write operations, the DL field in the TCCB 170 specifies the amount of data to be transmitted during operation, which may include all required pads and CRC bytes. For bidirectional operations, the DL field in TCCB 170 specifies the amount of data to be transferred for the write data transfer portion of its operation and the BRDL field specifies the amount of data to be transferred for the lead data transfer portion of that operation . These quantities may contain all requested pads and CRC bytes.

During a write or bidirectional data transfer, the output data is transferred to the control unit 118 on a transport exchange associated with the TCW I / O operation at one or more transport-data IUs 310. In one embodiment, except for the first write transport-data IU 310 of operation, when the first transfer-ready is disabled, the channel 128 transmits each transport-data IU 310 Request a transfer-ready IU from the control unit 118 before it is ready. The control unit 118 may request additional data by sending additional transfer-ready IUs until completing requesting all data specified by the DL field 186 of the TCCB 170 for a write operation. For a write operation, the next IU transmitted by the control unit 118 after completion of the data transfer specified by the DL field 186 in the TCCB 170 is a transport-response IU. For bi-directional operation, the next IU transmitted by the control unit 118 following completion of the data transmission specified by the DL field 186 in the TCCB may be a transport-data IU or a transport-response IU.

During the read data transfer, the data is transferred to the channel 128 on the transport exchange associated with the TCW I / O operation at one or more transport-data IUs 310. The amount of data transmitted in each transport-data IU is determined by the control unit 118 and the total amount of data transferred in all the transport-data IUs for that operation is stored in the DL field 186, For bidirectional operations, any value may be set as long as the value in the BRDL field 188 is not exceeded. For read operations, if the amount of data transmitted by the control unit is less than the DL field in the TCCB, the DL residual count in the transport-response IU is the DL residual count, the amount of data transmitted by the CU, The difference between the two. If the remaining count provided by the control unit to the transport-response IU does not match the difference between the DL and the number of bytes actually received by the channel, the channel acknowledges the device-level protocol error.

For write and bidirectional operations, the DL remaining count in the transport-response IU will be the difference between the amount of data sent by the channel and the DL field in the TCCB. If the DL remainder count provided by the control unit in the transport-response IU does not match the difference between the DL and the number of bytes actually transmitted in the channel, the channel recognizes the device-level protocol error. For bi-directional operations, if the amount of data transmitted by the control unit is less than the BRDL field in the TCCB, the BRDL-remaining count in the transport-response IU is the difference between the amount of data transmitted by the CU and the BRDL field in the TCCB Will be. If the remaining counts provided by the control unit in the transport-response IU do not match the difference between the number of bytes actually received by the BRDL and the channel, the channel acknowledges the device-level protocol error.

For a write or bi-directional operation, when the first-transfer-ready is disabled, the channel transmits the transport-data immediately following the transport-command IU. For all transport-data IUs from the channel after the first transport-data IU and for all transport-data IUs from the channel when the first-transfer-ready is not disabled, Only after receiving will the channel send a light transport-data-IU. The channel will transmit the transport-data IU until all write data specified by the TCCB is transmitted after receiving each transmit-ready IU or until a transport-response IU is received.

For read or bidirectional operation, the control unit sends at least one transport-data IU to the channel to transmit the specified lead data for its operation.

For bidirectional operations, the control unit selects and transmits the first transport-data IU when the first-transfer-ready disabled is not in effect. The control unit sends to the channel to request the transport-data IU - either the ready IU or the transport-data IU to the channel. If the disable of the first-transfer-preparation is in effect for its operation, the channel transmits the transport-data IU following the transport-command IU.

For bidirectional operations, both write and read data transfer can be performed. The write data transfer and the read data transfer can be performed as described above. Data transmission between the channel and the control unit to request a write transport-data IU is controlled by the control unit when the disable of the first-transfer-preparation is in effect except for the first transport-data IU, Lead transport - controlled by sending a data IU or by sending a transmit-ready IU.

The order in which data received in the transport-data IU is stored in the host storage as compared to the order in which the data is fetched from the host storage and transmitted to the transport-data IU may not be predictable for bidirectional operation.

When the channel is transmitting the first Transport-Data IU, or when the control unit is requesting the Transport-Data IU from the channel by sending a Transmit-Ready IU, The data sent to the transport-data IU may be for write DCWs that are executed subsequent to the execution of the read DCWs in the TCA.

As shown in FIG. 15, one or more intermediate CRC words 320 may be present in the transport-data IU transmitted by the channel 128. The intermediate CRC words 320 provide CRC checking of the data areas before transmission of the entire data area specified by the TCA 180. [ The COB CRC word 322 may be present in the transport-data IU 310 when the COB 222 is transmitted to the transport-data IU 310.

Referring again to FIG. 14, in step 305, the TCW I / O operation is terminated by channel 128 or control unit 118. Channel 128 may initiate the termination of the TCW I / O operation as a result of an abnormal condition or as a program-initiated termination. The control unit 118 may initiate the end of the operation as a result of the completion of the operation or as a result of the abnormal condition detected during the execution of the command. The control unit 118 may initiate the termination of the TCW I / O operation by sending a transport-response IU, or, in the case of certain errors, discarding the exchange. In one embodiment, the control unit 118 may initiate the termination of a TCW I / O operation under any of the following circumstances: all DCWs in the TCA 180 (and TCAX if specified) 202) has been executed; DCW-Incorrect-Length condition detected for DCW when incorrect length facility is supported and SLI flag 214 is set to zero; Unit check condition should be detected; There must be an abnormal condition such as a transport error; Or other error requiring discarding the exchange.

16-18 illustrate an exemplary transport response IU 330 that may be transmitted by the control unit 118. As shown in FIG. The transport response IU 330 provides a state for TCW I / O operation, which includes a normal ending status or, when an abnormal condition is detected, And a termination status indicating the cause of the failure. The transport response IU 330 may also include an extended status field, which further provides a status for operation. The transport response IU may or may not close the transport exchange. In one embodiment, whether or not the transport exchange is closed by the transport response IU is indicated in the FC-FS-3 header. If the transport exchange is not closed by the transport response IU, the channel can send the transport-acknowledgment IU, which closes the transport exchange after receiving the transport response IU.

In one embodiment, the transport-response IU 330 includes an SB-4 header 332 followed by a status field 334, a status LRC 344, and, for example, 32 bytes to 64 bytes And an optional extended-state field 346 for selecting the extended state. A 4-byte extended-state LRC field 340 may be provided as the last word of the transport-response IU 330 if an extended status (ES) is provided. If the number of extended-status bytes is not in one word range, pad bytes are added to the extended-state to round to the next word range. The SB-4 header 332 has a format similar to the format of the transport command IU and is set equal to the SB-4 header in the transport command IU for this exchange.

17, one embodiment of the status area 334 is, for example, 20 bytes and holds information regarding the TCW I / O operation. The "Status Flags 1" field 336 contains one or more exception codes, which are set by the control unit 118 to report abnormal conditions detected during TCW I / O operation. Exemplary codes include the following:

0 - Address - Device-level exception due to exception condition (Device-level exception)

2 - Link-level reject due to logical-path not-established condition

3 - Resetting event notification - A reset event occurs on the device associated with the logical path and the transport-command IU. When this code is set in the transport-response IU, the control unit requests a status confirmation for that state. If a status check is received, the reset event condition is reset at the device for that logical path; Otherwise, the reset-event condition remains pending;

4 - DEVICE - Detected Program Check / IFCC - The control unit detects a condition that can be reported by program check or IFCC. Errors corresponding to this category include a transport-command IU that has reached a corrupted state (e.g., TCCB integrity error), an invalid CRC detected for write data, and a logical path And a second I / O operation for the device address.

5 - DEVICE - Detected program check - The control unit detects an error in the content of the TCH

In one embodiment, state flags 1 336 include an incorrect length (IL) flag 338. [ When DCW-inaccurate-length facility is supported by the channel and control unit, bit 0 is the IL flag, and when set to 1, the TCW I / O operation has an incorrect-length for the DCW indicated by the DCW offset Indicates termination due to condition. If the DCW data count does not match the amount of data requested by the device for the write DCW, or if the DCW data count does not match the amount of data available in the device for the read DCW, an incorrect length is sent to the control unit 118 .

In one embodiment, if the DCW 202 includes an SLI flag 214, the IL flag 338 is only available if the SLI flag 214 is 0 and the device state includes a channel-terminated state without a unit- 1. When the IL flag 338 is set to 1 in the transport-response IU, the DCW offset identifies the DCW holding the incorrect-length condition and the DCW remaining count, if any, is sent for an incorrect-length DCW Lt; RTI ID = 0.0 > data transmission. Data transmission for DCWs that precede inaccurate-length DCW in the TCA, if any, would have been performed as described below.

When the DCW holding the incorrect-length condition is the lead DCW, the last transport-data IU sent to the channel contains the CRC for all the read data sent to the channel during the TCW I / O operation. If the write DCW precedes the incorrect-length lead DCW in the TCA, the data for the write DCWs would have been received by the control unit and the CRC checking would have been performed on the data. The data for the write DCWs in the TCA following the incorrect-length lead DCW will be transferred to the control unit if necessary to obtain the CRC for the write data and perform CRC checking.

Incorrect-length conditions are not recognized by the query command, the transmit-CRC-offset command, or the TTE command, regardless of whether the facility is supported by the channel and the control unit.

The transport response IU 330 may also include a Data Length Residual Count (DLRC) field 340. For write and bidirectional operations, the DL-residual count is a 32-bit, unsigned binary integer that indicates the number of bytes actually received from the DL field and channel in the transport- Specify the difference. For read operations, the DL-remaining count is a 32-bit, unsigned binary integer, which specifies the difference between the DL field in the transport-command IU and the number of bytes actually transmitted in the channel.

For bidirectional operations, a BRDL residual count field 342 may also be included in the transport-response IU 330. For bidirectional operations, the BRDL remainder count is a 32-bit, unsigned binary integer, which specifies the difference between the BRDL field in the transport-command IU and the number of bytes actually transmitted in the channel.

The Status Flags 3 field 344 may be used by the control unit 118 to provide additional information regarding the associated transport-mode operation. This field contains an Extended Status Sent (ESS) bit to indicate that an extended state has been sent to the transport-response IU, including possible sense data. . ≪ / RTI > The extended state includes extended status (ES) flags, which include fields such as an ES Type Code field. I / O exceptions (the extended-state area is an exceptional condition), the I / O state (the extended-state area holds the valid ending status for the transport-mode I / O operation) , And the query state (the extended-state region holds the state for the query operation), and the query state (holds the state for the query operation).

When the ES-type code in the ES flags is an I / O exception, the ES includes reason codes (RC). Exemplary reason codes include the following:

1 - TCCB Integrity error: The control unit has determined that the TCCB has arrived in a polluted state (except when exception code 4 is displayed in the status flags field 1);

2 - Invalid CRC detected: An invalid CRC was detected on the received data (except when exception code 4 is displayed in one of the status flags);

3 - Incorrect TCCB length specification (when exception code 5 is displayed in one of the status flags);

4 - TCAH specification error (when exception code 5 is displayed in one of the status flags);

5 - DCW explicit error: There is an error in the DCW specified by the DCW-offset in the extended state (except when exception code 5 is displayed in the status flags 1 field);

6 - Transmission - Directional Clear Error: The command specified by the DCW specified by the DCW - Offset field in the extended state specifies the direction of data transmission that does not match the transmission direction specified in the TCH, or both the R and W bits are in the TCH 1 and bidirectional data transmission is not supported by the control unit (except when exception code 5 is displayed in one of the status flags field);

7 - Transport-count clear error (except when exception code 5 is displayed in the status flags field 1);

8 - Two I / O operations are active: The second non-query TCCB has been transported to the device for execution while the I / O operation is active on the device. The RCQ field has no meaning. This reason code is provided when exception code 4 is displayed in the state flags 1 field; And

One or more entries in the 9-CRC-offset block indicate that the intermediate CRC is not at the proper location for the device and / or the command to be executed. However, when exception code 4 is displayed in one of the status flags field.

The extended state may also provide a Reason Code Qualifier (RCQ), which provides additional information about the reason (s) for the I / O exception. Other reason code qualifier types may be used for various types of errors, such as TCCB integrity errors, output data CRC errors, incorrect TCCB length indications, TCAH explicit errors, and DCW explicit errors. Exemplary RCQs for TCCB integrity errors include:

0 - no additional information;

1 - Data Count Error - The amount of data transferred for the Transport Command IU is not equivalent to the amount of data specified by the L1 field plus 8 in the TCH for control units that do not support bidirectional operations, Is not equal to the amount of data specified by the L1 field plus 8 or 9 in the TCH for the control units; And

2 - LRC error - LRC on transport-command IU is invalid.

Exemplary RCQs for DCW explicit error include:

1 - Reserved-field clear error: reserved field in DCW required to hold 0 holds non-zero value;

2 - flags - field command - chaining explicit error: command - chaining bit is 1 and the next DCW offset is the sum of all DCWs, some or all of which extend beyond the end of the TCA, or the command - chaining bit is 0, The remaining bytes remain in the TCA.

3 - Control - Data Count Specification Error: The CD count specifies the control data over the end of the TCA.

4 - TCOB DCW position error: the first TCOB DCW is not the first DCW in the TCA;

5 - TCOB DCW duplication error: one or more TCOB DCWs are specified within the TCA;

6 - TCOB DCW multiple-count explicit error: CD count and DCW count are both zero or not zero;

7 - TCOB DCW direction error: TCOB DCW is specified in the TCA and the W bit in the TCH is 0;

8 - TCOB DCW chaining error: The chain-command bit in the TCOB DCW is 0;

9 - TCOB count - explicit error: TCOB DCW has a non-zero CD count or a data counter that is not a multiple of four;

10 - TTE DCW position error: TCOB DCW was not specified and TCA met a TTE DCW other than the first DCW, or TCOB DCW was specified and the first TTE DCW was not the second DCW in the TCA;

11 - TTE DCW Duplicate Error: One or more TTE DCWs encountered in the TCA;

12 - TTE DCW CD-count specification error: Control - data count in TTE DCW specifies a non-zero value;

13 - TTE DCW data - count specification error: The data count in the TTE DCW specifies a value less than 8 or a value that is not a multiple of 4;

14 - TTE DCW direction error: TTE DCW is specified and the W bit in TCH is 0;

15 - TTE DCW chaining error: The chain-command bit in the TTE DCW is 0; And

16 - TCAX Explicit error: TTE DCW is specified and one of the following is true:

The length of TCA is 58 words or less, or

The length of the TCA is 59 words, the final DCW in the TCA specifies the control data, and the length of the control data extends beyond 59 words, or

The length of the TCA is the maximum length of 60 words and the last word in the TCA holds the first word of the DCW.

Exemplary RCQs for transmission-directional clear error include:

1 - Lead-direction clear error: DCW specifies the input action and the R bit in TCH is 0;

2 - Write-direction clear error: DCW specifies the output operation and the W bit in the TCH is zero. NOTE - The DCW specification is acknowledged when the TCOB or TTE DCW is specified and the W bit in the TCH is zero;

3 - Lead-write conflict: both R and W bits in the TCH are 1 and the control unit does not support bidirectional operations or the control unit supports bidirectional, but the transport-command IU does not have a BRDL field or Both the R and W bits are not one and the transport-command IU holds the BRDL field;

Exemplary RCQs for transport-count explicit error include:

1 - Lead-count clear error: For read operations, the DL field in the TCCB specifies a value that is not equal to the DCWs plus pad bytes in the TCA and the total count of data bytes specified by the CRC; For bidirectional operations, the BRDL field in the TCCB specifies a value that is not equal to the total count of data bytes specified by the Lead DCWs plus pad bytes in the TCA and the CRC;

2 - Write-count explicit error: The DL field in TCCB specifies a value that is not equal to the total count of data bytes specified by the write DCWs plus mid-pad bytes, the intermediate CRC, the final pad bytes, and the final CRC bytes in the TCA and; If the COB is included in the first transport-data IU of the write data transmission, the count includes the COB, all COB pad bytes and COB CRC bytes. If the TTE DCW is present in the TCA, the count also includes TCAX and TCAX CRC bytes.

The program check occurs when programming errors are detected by the channel subsystem. For the transport mode operation, programming errors can also be detected by the I / O device 116 and reported as program checks. The program check condition can be due to any of the following reasons:

Invalid TCW Specification: When one of the following conditions is detected, an invalid TCW specification is recognized:

1. Reserved fields checked for zeros in the TCW do not hold zeros.

2. A nonzero value is specified in the TCW format field.

3. The read and write bits in the TCW are all 1, the bit 10 of the TCW flags field is 0, the FCX-bidirectional-data-transfer facility is not installed, or the specified device does not support bidirectional data transfers.

4. Bit 10 of the TCW Flags field is 0 and the TCCB-Length field in the TCW specifies a length less than 12 or greater than 244.

5. Bit 10 of the TCW flags field is 1 and the write operations (W) bit of the TCW is 0, or the read operations (R) bit of the TCW is 0 or both.

6. Bit 10 of the TCW flags field is one and the designated subchannel is not associated with the control unit that was configured for transport fiber-channel-service requests.

When the TTE DCW is used, the device-detected program check is recognized when any of the following conditions exist:

1. When the TCOB DCW is not specified, the TTE DCW is not the first DCW in the TCA. When the TCOB DCW is specified, the TTE DCW is not the second DCW in the TCA.

2. TTE DCW is specified and write operation is not specified (ie, the W bit in TCW is zero)

3. The chain-command flag in the TTE DCW is zero.

4. One or more TTE DCWs are specified.

5. The control-data-count field in the TTE DCW does not hold zero.

6. The count field holds a value that is not less than 8 or a multiple of four.

7. One of the following is true for TCA:

The TCA does not have at least one DCW other than the transport-command DCW.

The TCA holds one or more DCWs that are not transport-command DCWs and the chain-command flag in the final DCW of the TCA is zero.

When TTE DCW is used and additional TCMI and / or output data come after TCAX, the following should be true; Otherwise, the device-detected program check can be recognized:

The output-TIDA flag (flags bit 7) in the TCW shall be one; or

When TIDWs are used for transmission of TCAX and for transmission of data, the embedded -CBC control shall be set to 1 in the last or only TIDAW used to transmit the TCAX. When TIDWs are used for the transmission of a unique TCAX, the embedded -CBC control does not necessarily have to be set in the final or unique TIDAW.

During the processing of the TCA, a TCCB content error may be detected when any of the following conditions are detected:

1. The first TCOB DCW met is not the first DCW in the TCA;

2. The second TCOB DCW will meet at the TCA.

3. When the W bit in TCAH is 0, the TCOB DCW is encountered at the TCA.

4. The TCOB DCW does not have a chaining flag set;

5. If the CD count and data count are all 0, the TCOB DCW is encountered;

6. If neither the CD count nor the data count is equal to zero, the TCOB DCW is encountered;

7. If the CD count is 0 and the data count is not a multiple of 4, then the TCOB DCW is encountered;

8. If the data count is 0 and the CD count is not a multiple of 4, then the TCOB DCW is encountered;

9. The TCOB DCW is not specified and the TTE DCW is not the first DCW in the TCA or the TCOB DCW is specified and the TTE DCW is not the second DCW in the TCA;

10. When the W bit in TCAH is zero, the TTE DCW is encountered at the TCA;

11. TTE DCW does not have a set of chaining flags;

12. The second TTE DCW is encountered at the TCA;

13. When the CD count is not zero, the TTE DCW is encountered;

14. When the data count is zero or not a multiple of four, the TTE DCW is encountered;

15. TTE DCW specifies that either of the following is true: the length of the TCA is 58 words or less; The length of the TCA is 59 words, the final DCW in the TCA specifies the control data, and the length of the control data extends beyond 59 words; Or TCA has a maximum length of 60 words and the last word in the TCA holds the first word of the DCW;

16. The DCW has a command that requests control data and the CD count field has a value of 0 or a value that specifies the data that passes the end of the TCA;

17. DCW has a non-zero CD count field and the command prevents control data from being provided;

18. During a write operation, the device encountered a command in the TCA that attempted to perform a read data transfer.

19. During a read operation, the device encountered a command in the TCA that attempted to perform a write data transfer;

20. The CC bit is 0 in the DCW and 3 or more unused bytes remain in the TCA;

21. The CC bit is set to 1 in DCW and the next DCW position is determined to be less than 8 bytes from the end of the TCA indication, and TCAX is not provided. Or TCAX has been provided; The next DCW position is determined to be less than 8 bytes from the end of the TCA indication;

22. For read or bidirectional operation, when the lead DCW in the TCA is current, the sum of all previous read DCWs and data counts for the current DCW plus all pads and CRC bytes is the DL field in the TCCB Exceeds or exceeds the BRDL field in the TCCB for bi-directional operations;

23. For read or bidirectional operation, when the final DCW in the TCA is current, the sum of all lead DCWs plus data counts for all pads and CRC bytes is not equal to the DL field in the TCCB, , It is not the same as the BRDL field in the TCCB;

24. For write or bidirectional operation, when the DCW in the TCA is current, all write DCWs plus all pad and CRC bytes (including all intermediate pads and CRC bytes), and if the COB is a transport The sum of the data counts for the COB, COB pad and COB CRC bytes, and if TCAX is present, for the TCAX, TCAX pad and TCAX CRC bytes, if included in the data IU, exceeds the DL field in the TCCB; or

25. For write or bidirectional operation, when the DCW in the TCA is current, all write DCWs plus all pad and CRC bytes (including all intermediate pads and CRC bytes), and if the COB is a transport If included in the data IU, the sum of the data counts for the COB, COB pad and COB CRC bytes, and if TCAX is present, for the TCAX, TCAX pad and TCAX CRC bytes is not the same as the DL field in the TCCB.

In one embodiment, links are established between the channel subsystem 114 and the control units 118 and / or devices 116 prior to performing the command mode or the transport mode operation. Each channel 128 in an I / O system having physical connections with one or more control units may be referred to as an "N_Port" having a unique identifier (a "N_Port ID"). Likewise, each control unit 118 may also be an N_Port with associated N_Port_ID. Both the channel 128 and the control unit 118 may include a plurality of channel images or control unit images, respectively. Each N_Port contains an address identifier assigned during initialization and execution of the login procedure. Explicit N_Port login may be performed by the N_Port Login (PLOGI) extended link service during the initialization process. When an N_Port performs an N_Port login with another N_Port, the N_Port is said to be logged in with another N_Port.

In one embodiment, link initialization between the channel subsystem and the control units is performed using a process login (PRLI) extended link service (ELS) protocol. Common embodiments of PRLI ELS, including the format of the PRLI ELS request and response, are described in "Fiber Channel: Link Services (FC-LS-2) " of T11 project 2103-D, Rev. 2.00, ), Which is incorporated herein by reference in its entirety, together with specific settings for FC-SB-4 as defined in the following sections.

During the PRLI procedure, the channel 128 supporting PRLI sends a request to each control unit 118 in its configuration that also supports the process login ELS, To determine if it supports these operations. In one embodiment, a PRLI request may be sent during channel initialization before the logical paths are established and also as a result of a process logout (PRLO). The PRLI ELS is used to exchange process login service parameters between the channel 128 and the control unit 118. When logical paths are set in the control unit, a PRLI ELS request can be sent to the control unit by the channel and applied to all set logical paths. Parameters can be exchanged between the PRLI request and the PRLI response between the channel and the control unit.

In one embodiment, if the control unit receives a PRLI ELS request to modify service parameters for a process login already in effect on the channel, the control unit sends a PRLI ELS request with a link service reject (LS_RJT) Reply. This LS_RJT response is sent with reason code hex'09 ', which means "it is not possible to make a command request at this time". After the control unit sends an LS_RJT, the control unit will send a process logout (PRLO) ELS request to the channel to cause a retry of the PRLI ELS request from the channel to be performed successfully.

Referring to FIG. 18, a PRLI request includes a service parameter page, which includes various fields used to set service parameters. For example, the service parameter page 400 may include a type code field 402, which identifies the transport mode or FC-4 protocol (e.g., to indicate the SB-4 protocol) lt; 1 > B '). The type code extension field 404 (e.g., byte 1 of word 0) is set to zero. The FC-LS-2 flags field 406 (e.g., bits 16-19 of word 0) may be set by the channel as follows:

Bit 16 - Originator Process Associator Validity: This bit is set to 0 by the channel and ignored by the control unit;

Bit 17 - Responder Process Associator Validity: This bit is set to 0 by the channel and ignored by the control unit;

Bit 18 - Established Image Pair: This bit is set to 0 by the channel and ignored by the control unit; And

Bit 19 - Reserved: This bit is set to 0 by the channel and ignored by the control unit.

The service parameter page may include additional fields such as the originator process stakeholder field 408 (e.g., word 1) and the responder process stakeholder field 410 (e.g., word 2) that are set to zero by the channel Lt; / RTI > The Maximum Initiation Delay Time field 412 (e.g., byte 0 of word 3) is set by the control unit as the initiation-delay time in a process logout (PRLO) request It holds a binary integer that specifies the maximum value that can be set in units of seconds. The PRLO request is used by the channel or control unit to terminate the transport mode operation between the channel and the control unit. The maximum start delay time value is typically based on the amount of time that the channel is able to delay starting the new I / O operations without interfering with the host system.

The FC-SB-4 flags field 414 (e.g., byte 3 of word 3 of the PRLI request page) contains one or more flags described below:

0 - Transport mode supported. When bit 0 is set to zero, the channel does not support transport-mode operations. When bit 0 is set to 1, the channel supports transport-mode operations.

1 - Reserved.

2 - DCW Incorrect Length (IL) Facility Supported. For example, when the IL flag is active (e.g., when bit 2 is set to one), the DCW IL facility is supported by channel 128. When bit 2 is set to zero, the DCW IL facility is not supported by channel 128. The DCW IL facility includes support for the servo-length indicator (SLI) flag 214 and the incorrect-length flag 338. Transport mode - When the supported bit (bit 0) is 0, bit 2 will be set to 0.

5 - Two-way data transmission supported. When the bi-directional transmission indication is active (e.g., when bit 5 is set to 1), bidirectional data transmission is supported by channel 128. When bit 5 is set to zero, bidirectional data transmission is not supported by the channel. This bit has only meaning when it is in transport mode - the supported bit is one.

7 - First Transfer Ready Disabled Supported. When bit 7 is set to 1, a first-transfer-ready-disable operation is supported by the channel. When bit 7 is set to zero, the first-transfer-ready-disable operation is not supported by the channel. Transport-Mode - Bit 7 will be set to 0 when the supported bit (bit 0) is zero.

When both the channel and the control unit indicate support for first-transfer-ready disabled, the channel transmits the first transport-data IU from the control unit. In the transport mode, the write data transfer is performed when the disablement of the first-transfer-preparation is in effect so that it can be transmitted to the control unit without having to do so. If the channel or control unit does not support disabling of the first transmission preparation, the disable of the first transmission-preparation is not in effect for the transport mode operations.

Referring to FIG. 19, in one embodiment, the PRLI response includes a PRLI Accept Service Parameter Page 420 that identifies the transport mode or FC-4 protocol (For example, set to hex'1B 'to indicate the SB-4 protocol) type code field 402 and a type code extension field 404 (e.g., byte 0 of word 0) that is set to zero Fields. The FC-LS-2 flags field 406 (e.g., bits 16-19 of word 0) may be set by the channel as follows:

Bit 16 - Originator Process Associator Validity: This bit is set to 0 by the control unit and ignored by the channel;

Bit 17 - Responder Process Associator Validity: This bit is set to 0 by the control unit and ignored by the channel;

Bit 18 - Established Image Pair: This bit is set to 0 by the control unit and ignored by the channel; And

Bit 19 - Reserved: This bit is set to 0 by the control unit and ignored by the channel.

The response code field 422 (e.g., bits 20-23 of word 0) holds a binary integer indicating the result of the PRLI request. Meanings of response code values are defined by FC-LS-2. A first Burst Size field 424 (e.g., bytes 0-1 of word 3) indicates that the disable of the first-transfer-preparation is supported by both the channel and the control unit, Holds a binary integer specifying the maximum amount of data allowed to be transmitted to the first Transport-Data IU for transmission (e.g., in units of 4k bytes). A value of 0 indicates that there is no first burst size limit. The first-burst size field 424 may be implemented by all control units that support disabling of the first-transfer-preparation.

The PRLI Accept Service Parameter Page 420 may also include an FC-SB-4 flags field 414 (e.g., byte 3 of word 3) Includes one or more defined flags as described:

0 - Transport mode supported. When bit 0 is set to zero, control unit 118 does not support transport-mode operations. When bit 0 is set to 1, control unit 118 supports transport-mode operations.

2 - DCW Incorrect Length (IL) Facility Supported. When bit 2 is set to one, the DCW-incorrect-length (IL) facility is supported by the control unit 118). When bit 2 is set to zero, the DCW IL facility is not supported by the control unit 118. The DCW-incorrect-length facility includes support for the SLI flag 214 and the incorrect-length flag 338. Transport mode - When the supported bit (bit 0) is 0, bit 2 will be set to 0.

5 - Two-way data transmission supported. When bidirectional data transfer indication is active (e.g., when bit 5 is set to 1), bi-directional data transfer is supported by control unit 118. When bit 5 is set to 0, bidirectional data transmission is not supported by the control unit 118. This bit has only meaning when it is in transport mode - the supported bit is one.

7 - First Transfer Ready Disabled Supported. When bit 7 is set to 1, the 1-transfer-ready-disable is supported by the control unit. When bit 7 is set to zero, the first-transfer-ready-disabled operation is not supported by the control unit. Transport-Mode - Bit 7 will be set to 0 when the supported bit (bit 0) is zero.

Thus, the channel subsystem and control unit can use login messages such as PRLI messages to provide indications to each other about their respective support for bi-directional data transmissions. The channel subsystem and / or control unit may also provide indications to the host system (e.g., OS 110). For example, an indication may be provided from the control unit to the OS that the control unit supports bidirectional data transmissions. In one embodiment, the channel subsystem provides an indication of channel subsystem and / or control unit capabilities, including the ability to support bidirectional data transmissions. For example, the channel subsystem may provide capability information in response to commands from the OS.

Examples of capability indications are shown in Figures 20 and 21. As shown in FIG. 20, the channel subsystem may transmit a channel path description block 500 to the OS in response to an OS command (for example, a STORE CHANNEL PATH DESCRIPTION command). The channel path description block 500 includes fields such as a channel path identifier (CHPID) field 502, a descriptor 504, and a channel description specific data (CDSD) field 506. 21, the exemplary CDSD field 506 is a word in the channel path description block 500 and indicates the maximum data length (e.g., the maximum data length supported for TCW / TCCB) field 508 . For example, bits 0-15 of the CDSD field 506 set to (00O1h) means that the maximum bytes per TCW / TCCB are 64k. The extended support field 510 (e.g., bit 31) indicates support for protocol or protocol extensions, such as the FCX protocol. Additional fields 512 (e.g., bits 16-30) may include information regarding channel subsystem capabilities. For example, the BIDI bit (e.g., bit 28) of field 512 indicates channel subsystem support for bi-directional data transmissions.

A more detailed description is given in US patent application Ser. No. 12 / 030,912 filed February 14, 2008, entitled "Determining Extended Capability of a Channel Path ", published as US Patent Publication No. 2009/0210557, "

Technical advantages and advantages of the exemplary embodiments include, in addition to I / O commands and assistance data located in the TCCB, additional commands as well as the ability to transmit transport assistance data to the control unit. The technical effects also include the ability to continue processing DCWs despite detection of an incorrect length condition, which allows the control unit to continue processing I / O commands without having to terminate I / O operations give. Other technical effects include the ability to transport the input and output data modes between the channel and the control unit during a single I / O operation.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. As used herein, singular forms, unless the context clearly dictates otherwise, are intended to also include the plural forms. The terms "comprises" and / or "including", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, Steps, operations, elements, components, and / or groups thereof, whether or not explicitly described in connection with the accompanying drawings.

The equivalents, materials, operations, and equivalents of all means or step plus function elements in the claims below shall be construed to include all structures, materials, or operations for performing a function in combination with other elements explicitly claimed . Although the description of the present invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations will become apparent to those skilled in the art without departing from the scope and spirit of the invention. The embodiments have been chosen and described in order to best explain the principles of the invention and its practical application and to enable those skilled in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

As those skilled in the art will appreciate, the present invention may be implemented as a system, method, or computer program product. Thus, embodiments of the present invention may be referred to solely as a hardware embodiment, entirely a software embodiment (including firmware, resident software, microcode, etc.), or generally a "circuit ",≪ RTI ID = 0.0 > hardware / software < / RTI > Further, embodiments of the present invention may take the form of a computer program product embodied in one or more computer readable medium (s) having computer readable program code therein.

Any combination of one or more computer readable media (s) may be used. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer-readable storage medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination thereof. More specific examples of computer readable storage media may include: an electrical connection with one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM) (EPROM or flash memory), an optical fiber, a portable compact disc lead-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this specification, a computer readable storage medium can be any type of medium that can hold or store a program used in conjunction with or in connection with an instruction execution system, device, or device.

The computer readable signal medium may include a propagated data signal having computer readable program code embodied therein, for example, as part of a baseband or as part of a carrier wave. Such propagated signals may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. The computer readable signal medium may not be a computer readable storage medium but may be any computer readable medium that can communicate, propagate, or transfer a program used in conjunction with or by an instruction execution system, device, or device.

The program code embodied on the computer readable medium may be transmitted using any suitable medium including, but not limited to, wireless, wired, optical fiber cable, RF, etc., or any suitable combination thereof .

The computer program code for performing the operations of the embodiments of the present invention may be written in any combination of one or more programming languages and these languages may include object oriented programming languages such as Java, Smalltalk, C ++, Quot; programming language or similar programming languages. The program code may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partially on the user's computer and partly on the remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer, which can be through any kind of network, including a local area network (LAN) or a wide area network (WAN). Or the connection may be made by an external computer, for example via the Internet using an Internet service provider.

Various aspects of the invention have been described with reference to the following flow chart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products in accordance with embodiments of the present invention. It should be understood that each block of flowchart illustrations and / or block diagrams and combinations of blocks in the flowchart illustrations and / or block diagrams may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or programmable data processing apparatus to cause instructions to be executed by a computer or other programmable data processing apparatus through a processor and / To produce means for implementing the specified functions / operations within the machine.

These computer program instructions may also be stored in a computer readable medium such as a computer or other programmable data processing device to produce a product including instructions that implement the functions / , ≪ / RTI > or other devices may be stored in a computer readable medium that can direct them to perform functions in a particular manner.

The computer program instructions may also be loaded into a computer, other programmable data processing apparatus, or other devices so that instructions that execute on a computer, other programmable data processing apparatus, or other devices may be stored in the flowchart and / The computer may cause a series of operating steps to be performed on a computer, other programmable data processing apparatus, or other devices to produce a computer implemented process to provide processes implementing the specified functions / operations.

The flow diagrams shown here are just one example. Many modifications may be made to the diagrams or steps (or operations) described herein without departing from the scope of the invention. For example, the steps may be performed in a different order, or the steps may be added, deleted or modified. All of these modifications are considered part of the claimed invention.

Although preferred embodiments of the present invention have been described, it should be understood that various modifications and improvements can be made by those skilled in the art to which the present invention is directed, within the scope of the following claims. These claims should be construed to maintain reasonable protection for the invention as originally described.

Claims (25)

A computer-readable medium comprising:
The computer readable medium comprising executable instructions for performing an I / O operation initiated by an input / output (I / O) operation instruction in a host computer system configured for communication with a control unit,
The computer readable medium comprising:
Sending a process login (PRLI) request message to the control unit, by the channel subsystem, to initiate a link between the channel subsystem and the control unit in the host computer system; The PRLI request message comprising one field, the field having a value indicating whether the channel subsystem supports bidirectional data transmission;
Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission;
Providing an indication to the host operating system that bi-directional data transfer is supported; and
In response to executing the I / O operation command received from the host computer system,
Collecting a plurality of commands associated with the I / O operation command received from the host computer system, wherein at least one of the plurality of commands specifies input data transfer and at least one of the plurality of commands Specify output data transfer -;
Transferring the plurality of commands to the control unit;
Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And
Receiving from the control unit at least one input data message comprising input data to be stored in main storage of the host computer system, the input data message relating to at least one of the plurality of commands specifying an input data transmission Readable by a processing circuit for performing the method comprising:
Computer readable medium. 2. The method of claim 1, wherein the plurality of commands is a plurality of device command words (DCW), each associated with one I / O command, Wherein the TCW includes a Transport Command Control Block (TCCB) address field and the TCCB address field is an address of a TCCB in the main storage of the host computer system Wherein the TCCB comprises a plurality of DCWs, at least one of the DCWs specifying an input data transmission and at least one of the DCWs specifying an output data transmission
Computer readable medium. 3. The method of claim 2, wherein transmitting the plurality of commands comprises transmitting the TCCB comprising the plurality of DCWs to the control unit
Computer readable medium. 4. The method of claim 3, wherein the indication is configured to specify whether a first-transfer-ready disabled condition is in effect, the method comprising:
Sending the at least one output data message to the control unit after transmission of the TCCB and prior to receiving at least one message from the control unit in response to the first transfer-ready condition being in effect; ; And
Further comprising receiving the at least one message from the control unit prior to transmitting the at least one output data message in response to the first-transfer-ready-disable condition not being effected
Computer readable medium. 5. The method of claim 4, wherein the message from the control unit comprises one of a transfer-ready message requesting the channel subsystem to transmit the output data and the input data message
Computer readable medium. 3. The method of claim 2, wherein the TCCB is included in a transport command information unit (IU) transmitted to the control unit, the transport command IU includes a transport command header (TCH) Wherein the field indicates whether the channel subsystem is requesting bi-directional data transmission
Computer readable medium. 7. The method of claim 6, wherein the TCCB includes a write data length (DL) field that specifies an amount of output data to be transmitted and a bidirectional lead data length (BRDL) field that specifies an amount of input data to be transmitted
Computer readable medium. 8. The method of claim 7, further comprising the step of receiving, from the control unit, a transport response message indicating that the I / O operation is terminated, in response to the control unit not supporting bidirectional data operations Wherein the transport response message indicates that the control unit detects that both the R (R) and W (W) bits in the conditions TCH are set to 1 and the TCCB does not include the BRDL; And wherein the control unit detects that the R bit and the W bit are both set to one and the control unit does not support bi-directional data transmission.
Computer readable medium. 8. The method of claim 7, further comprising the step of receiving from the control unit a transport response message indicating that the I / O operation has ended, the transport response message comprising:
A Data Length Residual Count (DLRC) field that specifies a difference between a DL field value in the TCCB and an amount of output data received by the control unit; And
And a BRDL-remaining count specifying a difference between the BRDL field value in the TCCB and the amount of input data transmitted by the control unit
Computer readable medium. 10. The system of claim 9, wherein the channel subsystem comprises:
The DLRC value does not match the difference between the DL field value in the TCCB and the amount of output data sent to the control unit; And
Detecting an error in response to at least one of a BRDL residual count value not matching a difference between the BRDL field value and an amount of input data received from the control unit
Computer readable medium. 3. The method of claim 2, wherein the PRLI request message indicates to the control unit a request to indicate whether the control unit supports a transport mode protocol, Supports the use of TCCB;
And the PRLI request message includes a field indicating whether the control unit supports the transport mode protocol
Computer readable medium. An apparatus for performing an I / O operation initiated by an input / output (I / O) operation command in a host computer system configured for communication with a control unit, the apparatus comprising:
Sending a process login (PRLI) request message to the control unit, by the channel subsystem, to initialize a link between the channel subsystem and the control unit in the host computer system, The PRLI request message comprising one field, the field having a value indicating whether the channel subsystem supports bidirectional data transmission;
Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission;
Providing an indication to the host operating system that bi-directional data transfer is supported; And
In response to executing the I / O operation command received from the host computer system, performing a method comprising:
Collecting a plurality of commands associated with the I / O operation command received from the host computer, wherein at least one of the plurality of commands specifies an input data transfer and at least one of the plurality of commands is an output Specify data transfer -;
Transferring the plurality of commands to the control unit;
Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And
Receiving from the control unit at least one input data message comprising input data to be stored in main storage of the host computer system, the input data message relating to at least one of the plurality of commands specifying an input data transmission Containing
Device. 13. The method of claim 12, wherein the plurality of commands is a plurality of device command words (DCW), each associated with one I / O command, Wherein the TCW includes a Transport Command Control Block (TCCB) address field and the TCCB address field is an address of a TCCB in the main storage of the host computer system Wherein the TCCB includes a plurality of DCWs, at least one of the DCWs specifying an input data transmission and at least one of the DCWs specifying an output data transmission
Device. 14. The system of claim 13, wherein the indication is configured to specify whether a first-transfer-ready disabled condition is in effect, the host computer system comprising:
Sending the at least one output data message to the control unit after transmission of the TCCB and prior to receiving at least one message from the control unit in response to the first transfer-ready condition being in effect; ; And
Receiving the at least one message from the control unit prior to transmitting the at least one output data message in response to the first-transfer-ready-disable condition not being in effect
Device. 14. The method of claim 13, wherein the TCCB is included in a transport command information unit (IU) transmitted to the control unit, the transport command IU includes a transport command header (TCH) Wherein the field indicates whether the channel subsystem is requesting bi-directional data transmission
Device. 16. The method of claim 15, wherein the TCCB includes a write data length (DL) field that specifies an amount of output data to be transmitted and a bidirectional lead data length (BRDL) field that specifies an amount of input data to be transmitted
Device. 17. The method of claim 16, wherein the host computer system is further configured to: receive, from the control unit, a transport response message indicating that the I / O operation is terminated, in response to the control unit not supporting bidirectional data operations Wherein the transport response message is configured such that the control unit determines that the R-bit and the W-bit in the conditions TCH are both set to 1 and the TCCB does not include the BRDL To do; And wherein the control unit detects that the R bit and the W bit are both set to one and the control unit does not support bi-directional data transmission.
Device. 17. The method of claim 16, further comprising the step of receiving from the control unit a transport response message indicating that the I / O operation is complete, wherein the transport response message includes a DL field value in the TCCB, A Data Length Remaining Count (DLRC) field specifying a difference between the amount of output data received by the control unit and a BRDL field value in the TCCB and the control unit And a BRDL-residual count specifying a difference between the amount of transmitted input data, the channel subsystem comprising:
The DLRC value does not match the difference between the DL field value in the TCCB and the amount of output data sent to the control unit; And
Determining an error in response to at least one of a BRDL-remaining count value not matching a difference between the BRDL field value and an amount of input data received from the control unit (recognize)
Device. A method for performing an I / O operation initiated by an input / output (I / O) operation command in a host computer system configured for communication with a control unit, the method comprising:
Sending a process login (PRLI) request message to the control unit, by the channel subsystem, to initialize a link between the channel subsystem and the control unit in the host computer system, The PRLI request message comprising one field, the field having a value indicating whether the channel subsystem supports bidirectional data transmission;
Receiving a PRLI response message from the control unit, the PRLI response message comprising a field, the field having a value indicating whether the control unit supports bidirectional data transmission;
Providing an indication to the host operating system that bi-directional data transfer is supported; and
Performing one method in response to executing the I / O operation command received from the host computer system, the method comprising:
Collecting a plurality of commands associated with the I / O operation command received from the host computer system, wherein at least one of the plurality of commands specifies input data transfer and at least one of the plurality of commands Specify output data transfer -;
Transferring the plurality of commands to the control unit;
Transmitting to the control unit at least one output data message including output data to be transmitted to the control unit, the output data message associated with at least one of the plurality of commands specifying output data transmission; And
Receiving from the control unit at least one input data message comprising input data to be stored in main storage of the host computer system, the input data message relating to at least one of the plurality of commands specifying an input data transmission Containing
Way. 20. The system of claim 19, wherein the plurality of commands is a plurality of device command words (DCW) each associated with one I / O command, Wherein the TCW includes a Transport Command Control Block (TCCB) address field and the TCCB address field is an address of a TCCB in the main storage of the host computer system Wherein the TCCB includes a plurality of DCWs, at least one of the DCWs specifying an input data transmission and at least one of the DCWs specifying an output data transmission
Way. 21. The method of claim 20, wherein the indication is configured to specify whether a first-transfer-ready disabled condition is in effect, the method comprising:
Sending the at least one output data message to the control unit after transmission of the TCCB and prior to receiving at least one message from the control unit in response to the first transfer-ready condition being in effect; ; And
Further comprising receiving the at least one message from the control unit prior to transmitting the at least one output data message in response to the first-transfer-ready-disable condition not being effected
Way. 21. The method of claim 20, wherein the TCCB is included in a transport command information unit (IU) transmitted to the control unit, the transport command IU includes a transport command header (TCH) Wherein the field indicates whether the channel subsystem is requesting bi-directional data transmission
Way. 23. The method of claim 22, wherein the TCCB comprises a write data length (DL) field that specifies an amount of output data to be transmitted and a bidirectional lead data length (BRDL) field that specifies an amount of input data to be transmitted
Way. 24. The method of claim 23, further comprising the step of receiving from the control unit a transport response message indicating that the I / O operation is terminated, in response to the control unit not supporting bidirectional data operations Wherein the transport response message indicates that the control unit detects that both the R (R) and W (W) bits in the conditions TCH are set to 1 and the TCCB does not include the BRDL; And wherein the control unit detects that the R bit and the W bit are both set to one and the control unit does not support bi-directional data transmission.
Way. 23. The method of claim 22, further comprising the step of receiving from the control unit a transport response message indicating that the I / O operation is completed, wherein the transport response message includes a DL field value in the TCCB and a & A Data Length Remaining Count (DLRC) field specifying a difference between the amount of output data received by the unit and a BRDL field value in the TCCB, And a BRDL-remaining count that specifies the difference between the amount of input data that has been input. The channel subsystem comprising:
The DLRC value does not match the difference between the DL field value in the TCCB and the amount of output data sent to the control unit; And
Determining an error in response to at least one of a BRDL-remaining count value not matching a difference between the BRDL field value and an amount of input data received from the control unit (recognize)
Way.

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