JP2000163246A - Storage device subsystem having fifo function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer data through a storage device such as a disk drive in data transfer between systems and also to provide a disk drive provided with plural interfaces with a FIFO mechanism. SOLUTION: This storage device subsystem 3 has two interfaces 31 and 32, and only sequential access from each host is allowed for a disk 33. That is, once a host 1 writes data to the disk 33, the host 1 is controlled not to be capable of rewriting data in a corresponding address unless a host 2 reads the data out of the corresponding address. Thus, the disk 33 functions as a FIFO.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage subsystem used for an information processing system or the like, and more particularly, to a storage subsystem having an interface according to a plurality of data formats.

[0002]

2. Description of the Related Art In recent years, "downsizing", which uses a small computer such as a personal computer or a workstation to perform tasks conventionally performed on a mainframe, has been actively performed. A large amount of information has been stored in the mainframe due to the business performed conventionally, and there is a demand for accessing the information stored in the mainframe from a small computer. Conventionally, regarding data transfer between a plurality of computer systems, IEEE (Institute of El
Ethernet specified by ectrical and Electronics Engineers (802) is widely used.

[0003]

The Ethernet is widely used for data transfer between different types of computers because it is adopted by various computers. However, since a large number of computers are connected to the network, the Ethernet between the two computers is used. Transfer of large amounts of data in a computer is not desirable. Another problem is that the transfer speed of the network is relatively low.

[0004] Data transfer can be realized by exchanging data between a plurality of computers via a disk device having a plurality of interfaces. However, a normal disk device has functions required for data transfer between hosts. Not equipped. For example, when there is a disk device C shared by the host A and the host B, the host A
Even if data is written to the disk drive C, the host B cannot recognize which position of the data on the disk drive C should be read, so that data transfer via the disk drive C is impossible.

An object of the present invention is to provide a storage subsystem which can perform data transfer via a storage device typified by a disk device, instead of a network which has been conventionally used for data transfer between systems. It is in.
Further, according to the present invention, a first-in first-out mechanism (FIFO) that enables the host A to write data in a disk device having a plurality of interfaces and the host B to appropriately read the written data in the order in which the host A writes data is provided. It is an object of the present invention to provide a storage subsystem provided with the same.

[0006]

The structure of a storage subsystem for solving the above-mentioned problems will be described below. A storage subsystem according to the present invention includes an interface for connecting to a first computer and a second computer, storage means (such as a disk or a semiconductor memory), and data transfer between the interface and the storage means. Has a control device to control. In the control device, data writing from the first computer to the storage unit and data reading from the storage unit from the second computer are received in parallel, and the storage unit stores the data in the first computer. As a first-in first-out (FIFO) mechanism to the second computer. Further, the control unit receives data writing from the second computer to the storage unit and data reading from the storage unit from the first computer in parallel, and stores the storage unit in the first computer. May be operated as a first-in first-out (FIFO) mechanism between the first computer and the second computer.

In order to operate as such a FIFO mechanism, a first device connected via the interface is required.
Alternatively, access to the storage means from the second computer is limited to only sequential writing or sequential reading, that is, continuous writing or reading instructions from the first and second computers to the storage means are received. In such a case, it is preferable that the write address and the read address accompanying each instruction be sequential. Further, the control means makes the storage means look to the first and second computers as a disk larger than the actual disk capacity.
For example, when a capacity inquiry command (such as modesense in SCSI) is received from the first and second computers, the storage subsystem returns a capacity larger than the capacity of the storage means, such as a disk device, of the storage subsystem. Further, when a write request is actually received, the data is sequentially written, and when the write position exceeds the capacity of the actual storage means, the processing returns to the head of the storage means, and the writing is continued from there. . Similarly, when sequential reading is performed on the storage unit, if the read position actually exceeds the capacity of the storage unit, the process returns to the beginning of the storage unit and continues reading from there.
In this way, the storage unit operates as a storage unit having a larger capacity than the actual storage unit.

Further, the first computer performs writing, and
When the writing position to the actual storage means returns to the beginning,
If the previously written data has not yet been read from the second computer, writing from the first computer is not allowed until the previously written data has been read from the second computer. Conversely, when data is not written from the first computer to the disk reading position when the second computer performs reading, reading from the second computer is not performed. As a result, the present storage subsystem is provided with a first-in first-out (FI-FI) between the first computer and the second computer.
FO).

The storage means may be made to look like a volume that can only be written from the first computer and can only be read from the second computer, or the storage means can be read only from the first computer and read only from the second computer. From the computer, it seems that the volume is writable only,
Unauthorized access to the volume operating as the FO mechanism may be prevented.

Furthermore, even when the interface of the storage subsystem has an interface for receiving data in the count key data format and an interface for receiving data in the fixed length block format, the FI
Implement the FO function. The first computer accesses the storage subsystem in the form of count key data,
It is assumed that the second computer accesses the storage subsystem in accordance with the fixed-length block format. At this time, when the second computer reads the record in the count key data format written by the first computer to the storage means, the control device causes only the data portion to be read as the data of the fixed-length block format. Has functions. Alternatively, when the first computer reads out the data in the fixed-length block format written in the storage means by the second computer, the first computer converts the data into the data of the count key data format and reads the data. As a result, F between computers having different data formats can be used.
An IFO function can be realized. At the same time as the count key data format and the fixed-length block format data conversion, character code conversion such as ASCII code and EBC
It is also possible to add functions such as mutual conversion of DIC codes.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration example of a computer system according to the first embodiment of the present invention. This computer system includes a host 1, a host 2, and a storage subsystem 3 connected to the host 1 and the host 2.

The storage subsystem 3 comprises an interface 31 connected to the host 1, an interface 32 connected to the host 2, a disk 33, a control memory 34, a control device 35, and a setting console 36. A plurality of disks 33 may exist.

Here, the interface between the host computers 1 and 2 and the storage subsystem 3 is a fixed-length interface (fixed-length format). In the fixed length format, each data is stored in an area called a block.
Each block has a fixed length of, for example, 512 bytes.
Each block has a block number (hereinafter referred to as LBA)
And specify the transfer length and access. The transfer length specifies the number of fixed-length blocks.

The storage subsystem 3 has a function of changing the role of the disk 33 in accordance with an instruction input from the setting console 36. As the role of the disk 33,
The device may be a device dedicated to the host 1, a device dedicated to the host 2, or a shared device usable by both the host 1 and the host 2. When it becomes a shared device, it also becomes a FIFO device that can be used for data transfer between the host 1 and the host 2.

The case where the disk 33 is set as a FIFO device will be described. When viewed from the host, the FIFO device appears as an extremely large disk that exceeds the capacity of the actual disk 33. For example, when the interface 31 and the interface 32 are SCSI interfaces, when the host 1 and the host 2 issue a modesense command to the storage subsystem 3,
The capacity will be returned. When the disk 33 is set as a FIFO device, a value indicating a larger capacity than the actual capacity of the disk 33 is returned. Further, only sequential access is possible from the host, and discontinuous access is not possible. Access must always be performed from the beginning, and subsequent access must be performed in order. As an implementation for this, when a command from the host is discontinuous access, a method of returning to the host as processing failure, or ignoring any address specified by the host on the storage subsystem 3 side and arriving data , And a method of sequentially accessing them. Hereinafter, in the present embodiment, the latter case will be described. Also, in order to prevent unauthorized access to the FIFO device 33, the host
There is also a function to make read only from the host, or read only from the host 1 and write only from the host 2.

Referring to FIG. 2, the control memory 34 will be described. The control memory 34 has a FIFO device table 40, and the table 40 holds flags 41 corresponding to each LBA. The LBA holding the flag 41 is not the LBA when the host views the disk 33 as a disk having a larger capacity than the actual capacity, but is the LBA on the actual disk 33. An LBA
When a write comes to the address position, the flag 41 corresponding to the LBA in the table 40 is set to 1. And
When the content of the address of the LBA is read from another host, the flag 41 of the table 40 is returned to 0. In the present embodiment, a flag is provided for each LBA, but other than that, a method may be used in which a flag is managed for each of a plurality of blocks.

Further, the control memory 34 has a read address table 42 and a write address table 43. The initial value is 0 for each. The read address table 42 indicates a read start LBA when reading from the FIFO device 33, and the write address table 43 indicates a write start LBA when writing to the FIFO device 33. These LBAs are also not the LBAs when the disk 33 is viewed from the host as disks having a capacity larger than the actual capacity, but the actual disk 3
3 on the LBA.

Referring to the flowchart of FIG.
The operation of the storage subsystem 3 when writing to the O-device comes will be described. First, before writing and reading to and from the FIFO device are started, the FIFO device is initialized. In the initialization, the control device 35 sets the contents of the control memory 34, the contents of the write address table 43, and the contents of the read address table 42 to 0, thereby creating a state where nothing is written in the disk device 33. Initialization is performed from the setting console 36 to F
This is performed by issuing an initialization command to the FIFO device or by issuing an initialization command from the host to the FIFO device.

When a write request is received from the host, the controller 35 looks at the write address table 43 and determines an LBA to be written (step 101). Next, referring to the contents of the flag 41 corresponding to the LBA,
It is checked whether it is 0 (steps 102 and 103). 0
In the case of (1), it is possible to write at the position of the LBA. If the flag is 1, the process waits until it becomes 0. Step 1
In step 04, the write data is written to the target LBA. In step 105, the flag 41 in the table 40 corresponding to the LBA written this time is set to 1. In step 106, 1 is added to the write address table 43. If the LBA described in the write address table 43 exceeds the maximum number of blocks of the disk 33, the contents of the write address table 43 are returned to 0 (steps 107 and 108). Thus, when the last block in the disk 33 has been written, the next write LBA is 0, that is, the head of the disk 33.

Next, the operation of the storage subsystem 3 when a read request is received from the host will be described with reference to the flowchart of FIG.

When a block read request comes first,
The control device 35 determines the LBA to be read by looking at the read address table 42 (step 201). Next, referring to the flag 41 of the read target LBA in the table 40, it is checked whether it is 1 (steps 202 and 20).
3). In the case of 1, since there is data to be read in the block of the LBA, the next step 204
Proceed to. If it is 0, it waits until it becomes 1. In step 204, the block of the target LBA is read, and in step 205, the flag 41 in the table 40 corresponding to the LBA read this time is set to 0. In step 206, 1 is added to the read address table 42. If the LBA described in the read address table 42 exceeds the maximum number of blocks of the disk 33, the content of the read address table 42 is returned to 0 (step 207,
Step 208). Thereby, when the last block in the disk 33 is read, the next read LBA is 0, that is, the head of the disk 33.

When the above operation is executed so that, for example, the host 1 performs writing and the host 2 performs reading, the host 2 can sequentially read the contents written on the disk 33 by the host 1 from the top. Also, for example, when data is written from the host 1 to all areas on the disk 33,
The next writing position is moved to the head, but by referring to the table 40 and checking the flag 41 before writing,
It is possible to suppress writing for an address that has not been read by the host 2 yet. When the reading of the host 2 is completed, the host 1 writes again from the beginning, and when the host 2 has read the entire area of the disk 33, it starts reading from the beginning of the disk 33. As a result, the disk 33 is
(First-in first-out mechanism: First In First Out) Conversely, even when the reading from the host 2 is earlier than the writing from the host 1, a reading request from the host 2 to an area to which the host 1 has not yet written can be suppressed,
Operate as FIFO.

In the above embodiment, the disk is used for writing and reading from the host. However, data written from one host only needs to be stored until it is read from the other host. No equipment is required. Therefore, the present invention can be realized by using a semiconductor memory used for a cache memory or the like instead of the disk.

Next, a second embodiment of the present invention will be described.

FIG. 5 shows a configuration example of a computer system according to the second embodiment of the present invention. This computer system includes a host 1, a host 2, and a storage subsystem 3 connected to the host 1 and the host 2.

The storage subsystem 3 comprises a CKD interface 1031 connected to the host 1, a fixed-length interface 1032 connected to the host 2, a disk 33, a control memory 34, a control device 35, and a setting console 36. . A plurality of disks 33 may exist.

In the fixed-length format used in the first embodiment, each data is stored in an area called a block. Each block has a fixed length of, for example, 512 bytes. Each block is accessed by specifying a block number LBA and a transfer length. The transfer length specifies the number of fixed-length blocks.

On the other hand, in the CKD format, the cylinder number (C
C), head number (HH), and record number (R)
To access the record. The minimum unit of access is a record. Hereinafter, the record address represented by the cylinder number, head number, and record number is referred to as CCH.
The address of the track represented by the cylinder number and the head number is referred to as CCHH. In the CKD format, one record is formed by a count section (hereinafter, referred to as C section), a key section (hereinafter, referred to as K section), and a data section (hereinafter, referred to as D section). The C portion contains the lengths of the CCHHR, the K portion and the D portion, and is always a fixed length. The K portion and the D portion are of variable length and have the length described in the C portion. A plurality of records are collected to form one track, but the track length is fixed.
The number of records entering a track differs for each track.

The storage subsystem 3 has a function of changing the role of the disk 33 in accordance with an instruction input from the setting console 36. As the role of the disk 33,
If the disk is a fixed-length disk that stores fixed-length data, C
It may be a CKD disk for storing KD data, or it may be a FIFO device for data transfer.
When the device becomes a FIFO device, it can be accessed from both the CKD interface 1031 and the fixed-length interface 1032. When there are a plurality of disks 33, the function can be set for each of them from the setting console 36.

FIG. 6A shows a data arrangement on a track in a general CKD disk device, and FIG. 6B shows a data format when CKD format data is stored in the storage subsystem 3 of this embodiment. In this embodiment, the disk 33 physically uses a fixed-length data format, and operates as a CKD disk.
KD format data is converted to a fixed length data format and stored.

HA (51) in FIG. 6A is a home address and indicates a track state and the like. R0C (52) is a count part of record 0, and R0D (53) is a data part of record 0, where user data is not usually stored.
R1C (54) and R1D (55) are each record 1
And the data section. There is an area called a gap where data is not stored between the fields, and the area is a delimiter. The content and gap of the portion C are created inside the disk device.

In the storage subsystem 3, the HA (51), R0C (52), and R0D (53) of all tracks are collectively stored in another area, and the HA (51), R0C (52), R0D (5
3) is made invisible. When a write is received from the CKD interface 1031 to the storage subsystem 3, the control unit 35 shifts the C and D portions of each record from the beginning of the fixed-length block to the left as shown in FIG. Store. In addition, the space between records is left blank, and in the example of FIG. 6B, LBA2 (62)
Although there is an empty area at the end of record 1 of record 2, record 2 starts from LBA3 (63). There may be a K portion (key) between the C portion and the D portion. However, here, a record without a key is considered, and the K portion does not exist.

Next, a case where the disk 33 is set as a FIFO device will be described. In a FIFO device, only data of a predetermined size can be accessed.
For example, when accessing from the CKD interface 1031, a record of an arbitrary size can be normally read and written. However, in the case of use as a FIFO device, the size is one type and is a multiple of the size of a fixed-length block. Access from the fixed length interface 1032 is also limited to one type of size, and is the same as the record size accessed from the CKD interface 1031. Further, the FIFO device allows only sequential access from the host, and discontinuous access is prohibited. Access is always performed from the beginning, and subsequent access must be performed in order. Further, when viewed from the host, the disk appears as an extremely large disk exceeding the capacity of the actual disk 33.

The case where writing to the FIFO device comes will be described. CKD interface 1031
When a write is received from the host 1, the C and K portions (if the K portion exists) are also passed from the host 1, and the control device 35 converts the C and D portions into a format as shown in FIG. Is done. Each record is written sequentially from the beginning, and when a record is written up to the last track of the last cylinder, the next written record is written again at the beginning. At this time, the cylinder number and the head number sent from the CKD interface 1031 are written in the C section. That is, actually, the disk 3
3, a record is written at the beginning of the disk 3. However, since the host 1 recognizes the disk 33 as having a larger capacity than the actual disk, the position information includes an address indicating the track next to the last track. Is written.
Thereafter, similarly to the position information of the record to be written, an address different from the actual address is written.

On the other hand, when a block is written from the fixed-length interface 1032, the LBA is specified. However, the fixed-length interface 1032 does not look like FIG. 6C with the image removed. Therefore, host 2
From, the block number where the data is written is the actual L
You can see something different from BA. Hereinafter, the block number seen from the host 2 is referred to as a device address 71 to distinguish it from the LBA in FIG. 6B. That is, the host 2 gives the device address 71 when the disk 33 is viewed as a disk having an extremely large capacity exceeding the actual capacity.

The control device 35 includes a fixed-length interface 1
032, the device address 71 and data are received.
Then, CCHHR is calculated from the device address 71 to create the C section. In the FIFO device, since each record is limited to a fixed length, CCHHR can be easily calculated from the device address 71. For example, when the number of tracks in one cylinder is a, the number of records in one track is b, and the device address given by the host is L, CC = L ＝ (a × b) HH = (L− (CC × a × b)) ÷ b R = L− (CC × a × b) − (HH × b) However, the decimal part is truncated by division.
After the creation of the C portion, the D portion is stored on the disk 33 together with the created C portion as a CKD format record as shown in FIG. 6B. The above equation can be used not only for conversion when the disk 33 is viewed as a disk having an extremely large capacity than the actual capacity, but also for conversion of the address on the actual disk 33. Also, based on the relationship of the above equation, C
A conversion formula from CHHR to a device address can also be derived.

Further, when data is written up to the last block, the next data is written at the head of the disk 33 in the same manner as writing from the CKD interface 1031. The C section created at this time has an address indicating the track next to the CCHH attached to the last block.

Referring to FIG. 7, the contents of the control memory 34 will be described. The control memory 34 has a table 40 for FIFO devices.
R and a flag 41 corresponding thereto. Note that the flag 4
The CCHHR holding 1 is not the CCHHR when the disk 33 is viewed as a disk having a larger capacity than the actual capacity from the host, but is the CCHHR in the image of FIG. When a record is written to a record of a certain CCHHR, the control device 35 sets the flag 41 corresponding to the CCHHR in the table 40 to 1 at the time when the record is written.
Then, when all the contents of the record are read from another host, the flag 41 is returned to 0. Here, the description is made in units of records, but management may be performed in large units such as tracks or cylinders.

Further, the control memory 34 has a read address table 42 and a write address table 43. The read address table 42 and the write address table 43 indicate the device address 71 or CCHHR when reading or writing from the FIFO device, respectively. CKD interface 1031
From the fixed-length interface 1032, the write address table 43
It is managed by CHHR, and the initial value is (CC, HH, R) =
(0, 0, 1). The read address table 42 is managed in units of the device address 71, and the initial value is 0. Note that these device addresses 71 and CCHHR are not device addresses or CCHHRs when the disk 33 is viewed from the host as disks having a capacity larger than the actual capacity, but are device addresses based on images actually allocated on the disk 33. Address and CCH
HR.

Next, the operation of the storage subsystem 3 when writing to and reading from the FIFO device will be described.

First, referring to the flowchart of FIG.
Processing when writing from the host 1 to the FIFO device will be described. Before starting writing and reading to and from the FIFO device, the FIFO device is initialized. In the initialization, all the flags 41 of the table 40 shown in FIG. 7 are set to 0 to create a state in which nothing is written in the disk device 33. Read address table 4
2 is to record the device address, and the initial value is 0
And The write address table 43 records CCHHR, and the initial value is (CC, HH, R) = (0,
0, 1). The initialization is performed by the control device 35 by issuing an initialization command to the FIFO device from the setting console 36 or issuing an initialization command to the storage subsystem 3 from the host.

When a write request is received from the host 1, CK
The C interface is referred to by the D interface 1031 and the CCHH
The R address is extracted and sent to the controller 35 (step 1
101). Next, in the control device 35, the transmitted CC
From the HHR, the actual write position CC on the disc 33
The HHR is calculated (step 1102). The cylinder number is calculated as (cylinder number specified by host) mod
(The number of cylinders of the FIFO device). FI
The number of cylinders of the FO device is the number of CKD cylinders in the image shown in FIG. The head number and record number do not need to be converted as described above. Thus, when writing is performed up to the last cylinder and the last track in the disk 33, the next writing position is the cylinder 0, that is, the head of the disk 33. Next, the contents of the write address table 43 are compared with the calculated CCHHR, and if they are different, an error is returned to the host (step 1103).

Next, the content of the flag 41 corresponding to the CCHHR to be written this time (calculated in step 1102) in the table 40 is referred to, and it is checked whether it is 0 (steps 1104 and 1105). In the case of 0, the control device 35 converts the CCHHR (calculated in step 1102) into LBA, and as shown in FIG.
A record is written to A (step 1106). In addition,
The CCHHR included in the C portion of the record to be written is the CCHHR given from the host 1. If the flag 41 is 1, the process waits until the flag 41 becomes 0 (step 110).
4, 1105). In step 1107, the table 40
The flag 41 of the record to be written is updated to 1.

Next, in step 1108, the record number R of the record written this time (calculated in step 1102) is checked to see if it is equal to the maximum number of records in the track. Fixed length 1 for FIFO devices
Since only the type of record length is handled, the maximum number of records in a track is always constant. If they are not equal, 1 is added to the record number R of the write address table 43 (step 1114), and the process ends. If they are equal, CCHHR of the write address table 43 is set to R = 1,
Further, 1 is added to the content of HH (step 1109).
Further, when HH becomes equal to or more than the maximum number of tracks in one cylinder (step 1110), 1 is added to the content of CC, and HH = 0 (step 1111). Further, C
If C is equal to or larger than the maximum number of cylinders of the disk 33 (step 1112), CC = 0 is set (step 1).
113).

Next, referring to the flowchart of FIG.
The processing when reading the FIFO device from the host 2 will be described. First, when a block read request comes from the host 2, the device address of the FIFO device is actually calculated from the LBA coming from the host 2 (step 1201). The device address can be calculated from (block number coming from the host) mod (the number of blocks of the FIFO device). The number of blocks of the FIFO device refers to the maximum value of address blocks in device address units that can be actually created on the disk 33 in the image of FIG. 6C.

Next, the calculated device address is compared with the value of the read address table 42, and if different, an error is made (step 1202). If they are equal, the CCH to be read from the calculated device address
HR is calculated (step 1203). The formula for calculating CCHHR from the device address has already been described. Next, it is checked whether the flag 41 of the read target CCHHR in the table 40 is 1 (step 120).
4, 1205). If it is 1, the process proceeds to the next step, but if it is 0, it waits until it becomes 1. Further, the data of the target CCHHR is read (step 120).
6) When all the block data included in the data of the CCHHR has been read, the flag 42 corresponding to the CCHHR is changed to 0 (step 1207). Next, if the write record length from the CKD interface 1031 is for one fixed-length block (one device address), one is added to the value of the read address table 42; The minute is added (step 1208).

If the value of the read address table 42 exceeds the maximum number of blocks of the FIFO device, the contents of the read address table 42 are returned to 0.
(Steps 1208 and 1209). This allows the FIFO
When the last block in the device has been written, the next write block number is 0, that is, the top of the FIFO device.

In FIGS. 8 and 9 described above, an example in which data is written from the host 1 and read by the host 2 to perform data transfer has been described. Next, processing when writing from the host 2 and reading by the host 1 will be described. Will be described.

First, referring to the flowchart of FIG.
Processing when writing from the host 2 to the FIFO device is described. Initializing the FIFO device before writing is the same as in the previous example. Host 2
When a write request is received from the host 2, the LBA (block number when the disk 33 is viewed as a disk having a larger capacity than the actual capacity) sent from the host 2 is used as a FIFO.
The device address of the device (actual block number on the disk 33) is calculated (step 1301). This calculation can be performed from (block number coming from the host) mod (the number of blocks in the disk 33).

Next, the calculated device address is compared with the value of the write address table 43, and if different, an error is made (step 1302). If they are equal, the write target position CC is calculated from the calculated device address.
The HHR is calculated (Step 1303). Next, the flag 41 of the write target position CCHHR in the table 40 is set to
Check whether it is 0 (steps 1304 and 130)
5). If the value is 0, the process proceeds to the next step. If the value is 1, the process waits until the value reaches 0. In step 1306, the write contents are written to the write target CCHHR of the FIFO device.
Write to the location. At the time of writing, the controller 35 converts the device address into the LBA of the disk 33, and writes the written contents in the format shown in FIG. 6B. Note that the CCHHR included in the C portion of the written content is obtained by using the device address given from the host 2 as CCHH in the above equation.
It is converted to R.

In step 1307, the flag 42 corresponding to the currently written CCHHR in the table 40 is set to 1. In step 1308, the write address table 43
To update. In this step 1308, as in the example of FIG. 8, the value to be added is determined depending on how many fixed-length blocks the write record length from the CKD interface 1031 corresponds to. If the value of the write address table 43 is equal to or larger than the maximum number of blocks of the FIFO device, the contents of the write address table 43 are returned to 0 (steps 1309 and 1310). Thus, when writing is performed up to the last block in the FIFO device, the next write block number is 0, that is, the FIFO
It is the head of the O device.

With reference to the flowchart of FIG. 11, the processing when the host 1 reads the FIFO device will be described. When a block read request is received from the host 1, the CKD interface 1031 refers to the C section given from the host 1, extracts a CCHHR address, and sends it to the control device 35 (step 1401). Next, the control device 35 calculates the actual read position CCHHR of the disk 33 from the transmitted CCHHR (step 1402). The cylinder number can be calculated from (cylinder number specified by the host) mod (the number of cylinders of the FIFO device). The number of cylinders of the FIFO device is the same as that described in step 1102 of FIG. The head number and the record number are used without being converted as described above. Thus, when reading up to the last cylinder and the last track in the disk 33, the next read position is the cylinder 0, that is, the head of the disk 33. Next, the contents of the read address table 42 are compared with the calculated CCHHR, and if they are different, an error is returned to the host (step 140).
3).

Next, the C to be read in the table 40
It is checked whether the flag 41 corresponding to CHHR is 1 (steps 1404, 1405). If it is 1, the process proceeds to the next step, but if it is 0, it waits until it becomes 1. CCHHR to be read in step 1406
Is read, and in step 1407, the CCH
The flag 41 corresponding to HR is updated to 0.

Next, in step 1408, the record number R of CCHHR, which is the position read this time, is checked to see if it is equal to the maximum number of records in the track. F
Since the IFO device handles only one type of record length with a fixed length, the maximum number of records in a track is always constant. If they are not equal, 1 is added to the record number R of the write address table 43 (step 1414), and the process ends. If they are equal, the write address table 4
The CCHHR of 3 is set to R = 1, and 1 is added to the content of HH (step 1409). Further, when HH becomes equal to or more than the maximum number of tracks in one cylinder, 1 is added to the content of CC, and HH = 0 (steps 1410 and 1410).
11). Further, when CC exceeds the maximum number of cylinders of the disk 33, CC = 0 is set (step 1412, 1
413).

By performing the operations of FIGS. 8 and 9 in parallel or the operations of FIGS. 10 and 11 in parallel, the storage subsystem 3 operates as a FIFO. Since the data formats of the host 1 and the host 2 are different from each other, the data format needs to be converted. This conversion is also performed in the storage subsystem.

When data is written from the host 1 or 2 to the FIFO device, the character code of the write data is converted and written, or when the host 1 or 2 reads data from the FIFO device, the data is read. The character code of the data may be converted and read. For this purpose, for example, step 104 in FIG. 3, step 204 in FIG. 4, step 11 in FIG.
06, step 1206 in FIG. 9, step 13 in FIG.
06, or code conversion may be performed when writing or reading is performed in step 1406 in FIG. As a result, the code used in the host 1 becomes E
In BCDIC, the code used by host 2 is ASCI
Even in the case of I, code conversion can be performed mutually.

[0058]

As described above, according to the storage subsystem of the present invention, the storage means can be used as a first-in first-out mechanism (FIFO) and can be used for high-speed data transfer between hosts. Further, by providing a data format conversion mechanism in the storage device, data transfer between computers of different data formats can be performed without any special conversion work on the computer side.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a storage subsystem to which the present invention is applied;

FIG. 2 is a diagram showing an example of a table and an address table held in a control memory in a storage subsystem.

FIG. 3 is a diagram showing a flow of a write process for a FIFO device;

FIG. 4 is a diagram showing a flow of a read process for a FIFO device;

FIG. 5 is a diagram showing a configuration example (a second embodiment) of a storage subsystem to which the present invention is applied;

FIG. 6 shows CKD on a disk in the storage subsystem.
Diagram showing how data is stored in a format and the data format seen by the host computer

FIG. 7 is a diagram showing an example of a table and an address table held in a control memory in a storage subsystem.

FIG. 8 is a diagram showing a flow of a write process for a FIFO device;

FIG. 9 is a diagram showing a flow of a read process for a FIFO device;

FIG. 10 is a diagram showing a flow of a write process for a FIFO device;

FIG. 11 is a diagram showing a flow of a read process for a FIFO device;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host, 2 ... Host, 3 ... Storage subsystem,
31 ... interface, 32 ... interface, 33 ...
Disk, 34: control memory, 35: control device, 36
... setting console, 40 ... table, 41 ... flag,
42 read address table, 43 write address table, 1031 CKD interface, 1032
... fixed-length interface, 51 ... HA, 52 ... ROC,
53 ... R0D, 54 ... R1C, 55 ... R1D, 56 ... R
2C, 57: R2D, 60: LBA0, 61: LBA
1, 62 ... LBA2, 63 ... LBA3, 64 ... LBA
4, 65 LBA 5, 71 device address.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Arakawa 1099 Ozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture Inside System Development Laboratory, Hitachi, Ltd. 5B065 BA01 CA07 CC08 CC10 CS06 CS10 ZA20 5B077 AA41 NN07 5B082 FA02

Claims (6)

[Claims] An interface for connecting to each of a first computer and a second computer; storage means; controlling data transfer between the interface and the storage means; And the data reading of the storage means from the second computer are received in parallel, and the storage means stores the data on a first-in first-out (FIFO) basis from the first computer to the second computer. A) control means for operating as a mechanism. 2. The storage device subsystem according to claim 1, wherein said control means writes data from said second computer to said storage means, and writes data from said first computer to said storage means. A storage subsystem which accepts reading in parallel and operates the storage means as a first-in first-out (FIFO) mechanism between the first computer and the second computer. 3. The storage subsystem according to claim 1, wherein said control means limits access to said storage means from said first computer or said second computer to sequential access. Characteristic storage subsystem. 4. The storage device subsystem according to claim 1, wherein the control device sets the capacity of the storage means to the first and second computers as a capacity larger than an actual capacity. A storage subsystem for receiving an access from the first and second computers to an area exceeding an actual capacity of the storage means. 5. The storage subsystem according to claim 2, wherein said interface includes an interface for receiving data in a count key data format, and an interface for receiving data in a fixed-length block format. Performs access to the storage unit in accordance with the count key data format through an interface that receives data in the count key data format, and the second computer communicates through the interface that receives the data in the fixed length block format. The controller accesses the storage means in accordance with a fixed-length block format, and the control device reads the data in the count key data format written to the storage means by the first computer when the second computer reads out the data. , Fixed-length block format data Data in a fixed-length block format written by the second computer to the storage means when the first computer reads the data as count key data format. A storage subsystem. 6. The storage device subsystem according to claim 2, wherein the control device converts a character code of data written by the first or second computer into the storage means and writes the converted character code. Alternatively, when the first or second computer reads data from the storage means, it controls to convert and read a character code.