JPH0673100B2 - Optical storage system and data transmission method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical storage system that allows a computer to store and read data from an optical medium such as an optical disk.

BACKGROUND OF THE INVENTION During the last 20 years or so, two major drivers have existed in the data processing industry. Together, these major drivers have revolutionized the way we handle the tasks of collecting, storing, and decoding information.

The first impetus is the expansion of technical knowledge, represented by the Microcomputer Chip. Computer power, which once required a room-filling device and power consumption in kilowatts, can now be exerted with a ridiculous silicon chip.

The second impetus is simply economic, a steady and rapid drop in the purchase price of this technology. Especially in the field of storage devices, as prices decrease and capacity increases,
There is an inevitable rush to use the newly found storage space and fill it with information. In this way, demand seems to exceed supply forever.

Unfortunately, for users who require exceptionally large amounts of data storage, advances in magnetic-based storage technology are beginning to lag, with headgear values, and theoretical design limits for immediate recording density. It is approaching as soon as possible.
As a result, there is a real demand for rapid innovation in the field of data storage technology.

Accordingly, the present invention is directed to an optical storage system that is compatible with current magnetic-based storage systems and can significantly increase the capacity of data storage systems.

Conceptually, the optical storage system of the present invention combines many of the outstanding features of magnetic disks and tapes. Like magnetic tape, optical systems can store vast amounts of data on relatively inexpensive media. Information that has been stored once, such as a magnetic disk, can be retrieved very quickly, either in serial mode or in direct access mode.

Due to its unique write-once medium, optical storage devices are extremely well-suited for applications where long-term data stability and reliability are required, coupled with permanent embedded audit clues. obtain.

Externally, the optical device is very similar to a standard disk device. Mechanically, there are some close relatives.
The optical disk is rotated at high speed by a drive motor, and the read / write mechanism is driven by a powerful voice coil positioner, much like a standard magnetic disk, to allow the surface of the optical disk to be read. To scan.

However, that is the only similarity. Writing to and reading from the disk is accomplished by a coherent beam of light, eliminating the physical contact between the read / write mechanism and the medium.

The input data stream is used to modulate the output of a powerful infrared laser diode when information is to be written to an optical storage medium. The radiant energy from the laser is
Focus on a fine spot on the surface of the spinning media, which then tunes with the modulation pattern applied to the laser diode to create a tiny mark on the active layer of the disk. To do.

A fairly low power He operated in the visible portion of the spectrum
Ne lasers are used to read optically recorded data. Light from the HeNe laser is directed onto the disk surface and its reflected light is measured by a series of photodiodes. The variation in the intensity of the reflected light corresponds to the presence or absence of the mark on the medium.

The data can be read back from the disk as soon as it is written to the disk. Any error detected at this point will result in immediate data rewriting. The combination of electronic circuitry and software ensures that the information is essentially error free.

Optical system is a command from the operator console, Job Control Language (JCL) attached to the application program
Statements, calls from within a program from a high level user language using the host system call method through a complete set of channel commands, etc. and are controlled by commands.

Optical storage systems have the advantage of significantly cooling data and power consumption in the computer room as significantly more data is stored online through a small volume unit. Moreover, the data storage capacity of the offline shelf space is much greater than the storage capacity obtained using magnetic tape or disk systems.

Based on accelerated lifetime testing, optical media have an expected useful life of 10 years, and optical storage subsystems have powerful built-in error detection and correction algorithms.

Optical storage media are unaffected by magnetic fields and can retrieve data at speeds comparable to immobile magnetic disks.

Further, looking at the amount of media required to store a given amount of data, optical storage devices are significantly cheaper per megabyte than either magnetic tape or magnetic disks.

The direct application of a computer to the control of optical storage systems is technically feasible, but at the expense of the expense and the fact that there is currently investment in magnetic storage system devices. Therefore, it is not economically practical.

Calculation of intersystem conversion costs for moth paramagnetic disk storage only and moth para optical storage only is prohibited.

Accordingly, it is an object of the present invention to provide a system in which current updated computer magnetic storage systems are compatible with optical storage systems.

In conventional magnetic storage systems, one or more magnetic disk systems are controlled by one or more storage directors by a control unit,
The control unit communicates with the host CPU via a channel such as a normal IBM channel.

Presently, there is a storage unit existing in the control unit, for example, in Louisville, Colorado, USA.
Storage Technology Corporation
The STC8880 control unit made by IBM and the IBM 3880, although programmable, do not allow the entire system to be directly adapted to allow the use of the optical storage system for the host computer. Furthermore, it is not possible to allow the host computer to use both the optical disk unit and the magnetic disk unit.

OBJECTS OF THE INVENTION Accordingly, the present invention combines an optical disk unit with a magnetic disk unit in a current storage system,
It is also intended to provide the minimum conversion means necessary to be able to use it.

In summary, in accordance with the present invention, the general adaptation required for a storage system is to provide microcode to the storage director used in the optical disk unit for the data to be stored or read from the optical disk unit, and further By providing the adaptation program in the host computer, the intended purpose can be achieved.

In view of the fact that the basic control system required to control an optical disk unit is completely incompatible with the basic control signal required to control a magnetic disk unit, the storage director used with an optical storage unit disk is , Microcode conversion is required. However, it has been found that simply adapting a storage director with such microcode cannot solve the problem.

Thus, in the present invention, the computer has a program associated with the data that is to be directed to or received from the storage director, the program being associated with the optical disk unit and thereby the hardware. To control the optical disk unit without modification of
It is possible to use a host computer.

The host computer then associates the data block with a storage medium of the type used for magnetic or optical data blocks, and when the data block is associated with the optical storage unit,
Control data according to additional urograms embedded in self.

As a result, as far as the user is concerned, it does not matter whether the data is stored in an optical or magnetic way, and conventional high-level languages are used in the normal programming context.

The system of the present invention has the advantage of increasing the storage capacity of an optical disk system without having to modify the hardware.

Since the read / write process used in an optical disk system is quite different from that of a magnetic disk system, it is clear that different types of control are needed for magnetic and optical disk space.

In magnetic disk systems, rewriting can be performed in incremental areas of storage space as desired. However, in the optical disk system, each incremental area of the optical disk, that is, the block, can be written only once, so that it has not been used for writing new data or changed data. You have to use the disk space. Similarly, for a given modified data, the already written disk space must be blocked. In this embodiment, the memory block is, for example, 7904 bytes.

Chapter 1 Structure of Embodiments The present invention will be disclosed in detail with reference to the accompanying drawings so that the present invention can be further understood.

FIG. 1 shows a simplified block diagram of a data storage system having the structure of the present invention. This system has a host CPU (10).

In the preferred embodiment of the invention, the CPU (10) is an IBM
A 370 or 308X mainframe computer, or a computer compatible with both. The computer (10) has a built-in MVS (Multiple Virtual Storage) disk operating system in itself. MV
S is an operating system owned by IBM Corporation.

The system also includes one or more optical disk unit ODUs (11). The host CPU is coupled to the optical disk unit via a channel (12) and a control unit (13) having a storage director.

The channel (12) is a block multiplexer or selector channel, a conventional IBM channel such as a computer communication link. Control unit (13)
Is a Type STC8880 storage control unit manufactured by Storage Technology Company of Louisville, Colorado, USA.
Or equipped with IBM 3880.

In this system, the host / CPU has a host and resident software (15) (hereinafter referred to as OPSAM).
Applies to ODU control. The storage director (14) of the control unit (13) has the control resident software indicated by the reference numeral (16), and the optical disk unit is the storage unit resident software indicated by the reference numeral (17). I have clothing.

The control unit (13) connects one or more additional storage directors (19) to the channel (12), for example for controlling one or more magnetic disk units (20). You can It has a channel command word to control the data transfer between the host computer and the storage director. The storage director decodes and executes the instructions from the book channel to control the interface between the book channel and the optical storage unit (11). The storage director also provides status signals to the host system to perform a diagnostic evaluation of the storage director and the optical storage unit.

In a typical system such as that shown in FIG. 2, the control unit (13) may include two or four storage directors. Each storage director can then communicate with up to eight optical disks, or storage units (11).

An optical disk is a storage device that has a large capacity and a high data transfer rate, thereby providing a low cost and reliable online data storage device.

Optical storage units differ from magnetic storage units in that they have an optical head system that sends laser light to both read and write to an optical disk.

Laser technology increases storage capacity to 4.0 gigabytes of user data per disk. Furthermore,
The optical disc may be enclosed within a removable optical media unit.

The optical storage unit responds to the instruction from the control unit (13) to position the access mechanism, read or write data, serialize or deserialize data, perform index control, and detect errors. And carry out corrections and corresponding functions.

The optical disk unit consists of an optical storage unit with built-in adaptive control electronics (optical element control). Unlike magnetic disk devices, the optical storage unit
It does not have a separate control module for interface requirements between devices. Since each optical storage unit has its own control electronics, the failure of the electronics affects only one unit and not the set of units.

The optical disk of the optical storage unit is rotated by the drive motor. The read / write mechanism is driven by a voice coil positioner to scan the surface of the optical disk. Laser light is used to both read and write through the optical disk. Therefore, there is no physical contact between the read / write mechanism and the medium.

The data stream modulates the output of the powerful laser diode when information is to be written to the optical disk. The laser light becomes parallel and focuses on a minute point on the surface of the rotating medium. Flicker marks are formed on the active surface layer of the optical disc to optically record the data flow pattern.

A helium neon laser is provided to optically record the data. Light from the laser is directed onto the surface of the optical disk, reflected from the optical disk, and measured by a group of photodiodes. The variation in the intensity of reflected light corresponds to the presence or absence of a mark on the medium.

As soon as the writing is complete, the data can be read back from the optical disk. The error detected at this point is idly fed, and the data is rewritten to a new area. The combination of the electronic circuit and the microcode ensures that the data is written without error.

The optical device control of the optical disk unit has the logic necessary for the two control interface functions and allows communication with two different storage directors. Thus, as shown in FIG. 3, each optical disk unit (11)
It can be in communication with either the storage director (14) or (14A), each allowing control by the host computer (10) (10A) via a channel (13) (13A). Each control interface provides the required interface path between the optical device control and its assigned storage director.

The optical media unit comprises an optical disk enclosed in a protective housing. The optical disc is protected from damage during handling, storage and shipping by the cartridge. Cartridges also have two exterior surfaces,
Display the serial number of the optical disk. The optical disk serial number is a series of unique alphanumeric characters assigned by the manufacturer prior to shipping. It is recorded on an optical disc, but appears on the cartridge in both readable and scannable bar code form.

The medium consists of an aluminum substrate of the type used in magnetic disks.

The optical disk provides a non-erasable recording surface for the data area without the need for pre-grooving. Light disk
It is divided into 716 concentric bands. Each band consists of a single manufacturer pre-recorded band positioning track and 48 user data tracks.

As the medium is organized into bands and tracks, the data blocks to be written are sequentially added to the remaining space in any band of the optical disc. This allows a group of separate data to be added to a single optical disk. Every data block
Once written, it can be addressed and retrieved serially or randomly, regardless of its position within the band or track.

Host-resident software, i.e. owned by IBM in the preferred embodiment of the present invention, is an IBM mainframe or compatible mainframe MVS / SP.
1.3 Performed in an operating system environment. It then controls how the end user interacts with the optical storage subsystem.

The host / resident software prepares for deciphering job / command language statements in the system (DD statement) and allocates and deallocates optical storage resources.

It includes operator console commands, and system
Programmer diagnostic commands are executed online to provide for a group of optical subsystem specific utilities and provide the optical storage subsystem with the access methods required to read / write.

The host interface, that is, the host resident software, is used as an interface in this way.
It works between the operating system and the optical storage subsystem.

The primary purpose of the host-resident software is to provide a means by which optical storage subsystem scheduling and support can be accomplished without disrupting the host system software environment.

The control unit software is responsible for decoding the channel command words originating from the host CPU and translating them into control interface commands that can be executed by the control unit (13).

There are five types of commands: control, write, read, test and diagnostic. Appendix A, attached, provides a summary of the commands within each category.

The control commands transfer control information, rather than data records, between the main memory and the memory director. This information can include an opcode that identifies the next action to be performed by the storage director or storage unit. It may also include parameters that limit the types of operations allowed or the data areas that can be recalled.

The CCW data address field indicates where to place the additional information required.

The read command transfers data from optical storage to main storage. Data is placed in main memory starting at the address specified in the data address field of the channel command and in ascending order of address.

The write command transfers data from main memory to optical memory. Data is fetched from main memory in ascending order of address starting at the address specified in the data address field of the command word.

The test command transfers 24 bytes of information from the storage director to the channel. The types of information provided by the test bytes are the error conditions detected in the preceding operation and the current state of the storage director and storage unit.

Diagnostic commands are used for maintenance purposes only.

The optical storage unit has a set of micro-processors, each of which has various functions such as dynamic defect pass-through processing, coarse search and fine search control, and general read / write processing. In charge of.

Memory unit resident software, control unit (13)
, Which translates the generated control command into an assembly language command that matches the internal micro-processor of the storage unit and causes the storage unit to perform the appropriate action and response.

Next, the configuration of preferable physical data used for the storage medium will be described in detail.

The general-purpose interface hardware of the channel (12) provides communication between the storage director and up to eight channels. Interface is a storage device 2
It is provided for one area, the microcontroller and the data path. There are 18 return signals and 19 forward signals received from the channel.

The control interface between the memory controller (13) and the optical memory unit is a chick chrysanthemum in which each memory dictionary is attached to a series of optical memory units (units 1 to 8) as shown in the attached instruction D. Pass 36 signals in a festoon shape.

Each optical storage unit has a dual path capability, which allows control of each unit to be shared between two storage dictionaries by two separate control interfaces.

Referring again to FIG. 1, another one of the control unit (13)
Two storage directors (19) can be used to control the magnetic disk unit (20).

As shown in FIG. 2, in a more complete system, a plurality of such magnetic disk units (20) can be controlled by a common control unit (13).

Chapter 2 Functional characteristics 2.1 Introduction This chapter describes the functional characteristics of both the memory controller and optical memory.

2.2 Storage Control Unit The storage control unit of the optical storage subsystem is a storage technology 8880 with a modified microcode.

The storage controller interface with the IBM S / 3700 OEM channel and storage control logic through the IBM control interface has a transfer rate of 1.5 MB or 3.0 MB per second.

This 8880 model has in-line and off-line fault inspection,
Has local and remote maintenance capabilities. The 8880 model also directs control interface protocols, translates channel command sequences, and presents storage device control logic paths. Model 8880 is 2 combined with optical storage device
It is possible to have one or four storage directors.

See the 8880 Disk Storage Control Subsystem Manual for more information.

2.3 Optical storage device The optical storage unit (Fig. 4) of the optical storage subsystem is a control electronics (optical element control (OD
C)]. Unlike magnetic disk devices, optical storage units do not have a separate control module that requires a device interface.

Since each optical storage unit has its own controlling electronics, the electronic deficiency affects only one unit and not the others.

The optical platter is rotated by a drive motor. reading/
The writing mechanism is driven by a voice coil positioner and scans the surface of the platter. Laser light is used to read from and write to the platter. There is no physical contact between the read / write mechanism and the media.

The data stream regulates the output of the high intensity write laser diode as information is written to the platter. The laser light is collimated and focused on a minute point on the surface of the rotating medium. Small marks are formed in the active surface layer of the platter to optically record the data stream pattern.

Helium neon (HeNe) reads the optically recorded data. Light from a HeNe laser is applied to the platter surface, reflected from the platter and measured by a series of photodiodes. The change in the intensity of the reflected light corresponds to the presence or absence of the mark on the medium.

As soon as the data is written, the data is read back from the platter. The error detected at this point jumps over the defective area and immediately rewrites the data in the new area. The circuitry and the microcode make the data error free.

2.3.1 Control Interface The optical device controller contains the logic necessary for two control interface functions and also enables communication with two different storage directors. Each control interface is
It provides the necessary interface path between the photoelement controller and the assigned storage director.

2.3.2 Self-checking capabilities In order to maintain the integrity of the data in the data path, there are two types of error detection methods. In other words, with the Paris Teitec
It is an error detection code (EDC). The EDC detects errors in the data buffer, media, and read / write channels.

2.3.2.1 Data buffer The data path is 16 bits wide through the machine and supports odd parity bits. At the point where data is fed into the path, a parity is generated and examined at various key positions on this path.

2.3.2.2 Error Detection Code During the write operation, all source data that entered the data buffer passes through the error detection code (EDC) generator. The generator calculates the number of bytes of the error check information input to the data buffer as a part of the logical block. The EDC information is written to the medium in the EDC resynchronizable data section and protected by ECC.

During a write operation, the readback check circuit feeds data to the EDC checker at the output of the read dynamics, defects, skipping buffers.
After the data and EDC bytes have passed through the checker, the result at the checker should be zero.

This check ensures data integrity on the return path from the input of the data buffer through the full write path to the readback circuit.

During the read operation, the data returned from the medium, placed in the data buffer and corrected by the functional microprocessor is examined as it is sent out from the data buffer. With this check, the error correction code (EC
It protects large errors that exceed the correction interval of C) and cause false correction of data (Chapter 6).

2.3.3 Optical media unit The optical media unit consists of an optical platter contained in a protective housing. Protects the optical platter so that the card carriage is not damaged during operation, storage and transportation. In addition, the cartridge provides two outer surfaces for displaying the serial number of the platter.

The platter serial number is a unique alphanumeric sequence assigned to the manufacturer prior to shipping. It is recorded on the platter but appears on the cartridge as a readable and scannable bar code.

Designed to last 10 years, the medium consists of an aluminum substrate with a precise diameter of 35.56 cm (14 inches) for magnetic disks. The optical platter has a non-erasable recording surface that does not require pregrooving the data area. The platter is divided into 716 concentric bands. Each band contains 49 tracks, which are made up of a factory recorded band positioning track (home address track) and 48 user data tracks.

As the medium is organized into bands and tracks, the data block to be written is placed in the space provided in one of the platter's bands. This allows a number of separate data sets to be placed in one optical platter. Once written, all data blocks are sent and retrieved in continuous or random order, regardless of their position within the band or track.

Chapter 3 Software 3.1 Software The software (programming) that supports the optical storage unit hardware and that together with the hardware constitutes the all-optical storage subsystem consists of three distinct and internally related layers. ing. These layers are the software of the host layer, controller layer and storage layer respectively. To get complete information about the software,
See Optical Storage Subsystem Application Programmer's Guide, System Reference Manual, System Programmer's Reference and Related Documents.

3.1.1 Host software The outermost layer of optical storage subsystem programming is the host software. For MVS / SP1.3 operating systems on IBM or IBM compatible mainframes, this software is implemented to affect the end user along with the optical storage subsystem.

The host software provides translations of JCL statements (DD statements) to allocate and deallocate optical storage resources. This host software translates and executes online operator console commands and system programmer diagnostic commands as well as provides the unique utility of many optical subsystems and read and write to optical storage subsystems. Provides the access method necessary for writing.

In short, the host interface acts as an interface between the host operating system and the optical storage subsystem. The primary purpose of the host interface is to provide a carrier for scheduling and supporting the optical storage subsystem without compromising host system software environmental conditions.

3.1.2 Controller software The intermediate layer of the optical storage subsystem software is stored in the 8880 Storage Control Unit. This software is
It interprets channel command words (CCWs) that occur in the host layer and translates these CCWs into control interface (CTL-I) commands that the Model 8880 can implement.

The next section lists and describes CCWs recognized by the control device. Chapter 9 describes the control interface.

3.1.2.1 Channel Command There are five basic types of commands. That is, control,
Write, read, sense, and diagnostic commands.

Table A-1 provides a summary of the commands in each category.

3.1.2.1.1 Control Commands Control commands transfer control information, rather than data storage, between main memory and storage directors. This information is provided by the storage director or storage unit. It contains instruction codes that specify the following actions:

This information may also include parameters to define the shape of the operation which consists of the authorized data area to be accessed. The CCW Data Address field specifies the location that contains the required additional information. Table A-2 gives a detailed description of the control commands.

3.1.2.1.2 Read command The read command transfers data from the optical storage device to the main storage device. In the main memory, data is stored in the order starting from the address specified in the data address field of the channel command word and increasing the address. Table A-3 details the read commands.

3.1.2.1.3 Write Command The write command transfers data from the main memory to the optical memory. Data is fetched from the main memory in the order of ascending addresses starting at the address specified in the data address field of the command word. Number A-
Table 4 details the write commands.

3.1.2.1.4 Sense Command The Sense command transfers 24 bytes of information from the storage director to the channel. Between the type of information provided by the sense byte, an error condition is detected in the operation and in the current situation of the storage director and the storage device. First
Table A-5 describes the sense commands in detail.

3.1.2.1.5 Diagnostic commands Diagnostic commands are used for maintenance purposes only. No. A-6
The table details the diagnostic commands.

3.1.3 Storage software The innermost layer of the optical storage subsystem programming code is
It is a memory unit software. The optical memory unit
Includes multiple microprocessors.

Each microprocessor is adapted to respond to different functions such as dynamic day skipping processing, coarse seek, fine seek control, and full read / write processing.

This layer of software takes the CTL-1 command generated in the 8880, translates it into an assembly language appropriate to the internal microprocessor of the memory unit, and elicits the appropriate actions and responses within the memory unit. It is a thing.

Chapter 4 Data Format 4.1 Physical Data Structure An appropriately defined physical hierarchy (Fig. 5) allows the optical storage subsystem to place data on the optical platter.
These structures are arranged in bands, tracks, sectors and blocks in order of decreasing complexity. These are described in the following sections.

4.1.1 Band The platter is divided into 716 bands, of which 713 bands are used as user data. These data bands are then divided into 717 use servo tracks, which serve as band delimiters and servo positioning ends.

The bands are addressed sequentially in ascending order, starting at the outer diameter and going from 0 to 715. There are three bands that serve special purposes, such as Indexes, Platta Table of Contents (PTOC) and Field Engineering.

4.1.1.1 FE Band Field Engineering Band (FE Band)
Is the outermost band (0). It contains a number of pre-recorded placement tracks used to check the reliability of the read channel (read / write channel).

4.1.1.2 Index Band The index band (band 1) is the only band that uses a short block of 128 bytes. The data in the index band is used to load the index memory.

The storage unit reads the index bands when the host CPU forms the "load index memory" CCW and assembles the index memory table in local RAM. The tables are constructed in such a way that the data arrangement within the special data is carried out as quickly as possible.

4.1.1.3 Content Platter Table Content Platter Table (PTOC) (Band 2)
Uses a long block of 7904 bytes. The host access method is used to partition the data into platters and determine each file contained in the platters.

4.1.2 Tracks Each band contains 49 concentric tracks. The first track is the home address track recorded at the time the platter is manufactured, while the remaining 48 tracks are used to record data. The tracks within a band are sequentially numbered from the outside to the inside of the band in ascending order.

The capacity of one track is 137018 user bytes, which is used for recording data, framing information, and error correction data. Space for framing and error correction methods and defect skips is about 11% of the total space. User data capacity is 11 per track
It is 8.560 bytes.

4.1.3 Sectors Each track is physically subdivided into a fixed number of equal length segments called “sectors”. A sector is the smallest unit of encoded information. The sector boundary is defined by the sector pulse that is derived independently from the data track information.
Predetermined accurately. There are four types of sectors.

1. Resynchronizable Data Sector (RDS) The RDS sector format is a 2-byte sync word (resync pattern) and the next 32 bytes of encoded user data, for a total of 34 bytes. Each RDS starts in a conventional radial position and each track has a fixed number of RDS cells. Due to the rotating arrangement, the RDS cells are numbered consecutively starting at the track index point.

2. Pre-angle A pre-angle is a sector that has the ability to provide variable frequency oscillator (VFO) synchronization during the beginning of a data block and during defect recovery.

3. Block Separator A block separator is a sector that contains a unique pattern to identify the beginning and end of a physical data block.

4. Exceptional Mark The Exceptional Mark is a sector whose unique pattern is designed to be written to identify media defects detected by the read back check while writing the data block. is there.

This mark is also used to identify incompletely written blocks at the end of the track.

4.1.4 Physical Data Block The physical data block (Fig. 6) is a continuous unit.
It is the order of sectors that are written together. A physical data block consists of a logical data block and a subsystem overhead. When a physical data block is read, it is converted into a fixed length logical data block.

However, during writing, the number of sectors containing physical data blocks changes due to detected media defects and dynamic defect skipping resulting from such discovery.

If no error is detected, the physical data block recorded on the track has the following format:

1. Block separator sector 2. Two pre-angle sectors 3. One pre-angle / resync data sector 4. One sector containing PID and one complement of PID (each is repeated once) 5. 247 resynchable data sectors containing 7904 bytes of user data (long block) or 4 resynchable data sectors containing 128 bytes of user data (short block). User data consists of a LID, a key and data.

6. Error detection code Resynchable data sector (34 bytes) 7. 6 resynchable data sectors containing error correction code for data (204 bytes) 8. Pre-angled sector 9. Block separator sector Pre-written Successive blocks are written starting with the following sector immediately after the last block separator of the data block.

4.1.5 Logical data block User data is written to or read from the data track of a fixed-length logical unit called a block. A block has a data length of 128 bytes (a short block used only for index bands) or
A byte sequence that is either 7904 bytes (long blocks).

The maximum number of long blocks per track is 15.
The long block logical structure consists of a physical ID (PID), a logical ID (LID), a key and data.
Short block consists of PID and data. In order to be better utilized, the user must be familiar with the structure of logical data blocks.

4.1.5.1 Physical ID The PID is an 8-byte physical ID supplied by the photoelement controller so that the data will be written to the platter.
An 8-byte entity is added to the front of each physical block to indicate the band number, track number, and associated record number within the band.

The PID is generated by the ODC when the data is written to the platter. When the read block and PID command or the read index band and PID command are tied, the PID can be returned as part of being recorded in the channel.

The four lower ordered bytes of the PID are called the physical search arm (PSA). The host uses PSA for address data on the platter. The PSA consists of a 2-byte band number, followed by a 2-byte related block number.

4.1.5.2 Logical ID LID is an 8-byte logical ID supplied by the host access method. The LID is part of the user record, which can be used as an address and is user selectable.

4.1.5.3 Key A key is a string of data of up to 64 bytes attached to user data by the host access method. The key is the part of the user record that is used to address the purpose and is user selectable.

4.1.5.4 Data Data is made up of a variable number of bytes so that it is made up of either short or long blocks. Short block is written only in the index band. All other bands contain only long blocks.

4.2 Records Records are the basic unit of transfer between the user and the host software access method. The maximum record length is 4 bytes. The maximum length of a logical record is indicated in each block as follows, depending on whether or not a key is recorded.

With key 2,017,280 to 2,001,920 bytes Without key 2,018,304 bytes 4.3 File A file is a user-defined collection of logical records, and the smallest collection of records that a user may be involved with. Files are continuously generated by the entry sequence. There is no limit on the number of records or the total number of bytes of data stored in the file.

Once generated, the file is expanded, even across the platter, if desired.

Through the job control language of the operating system, the user specifies the maximum logical record length of the file,
It can be set with or without a key. If the file is defined as a keyed file, the length of the key field and the offset for the key from the beginning of each logical record must be constant and specified. Records can be added to a keyed file only in the direction of increasing sequence of key sequences.

4.4 Access Mode There are three types of access modes provided by the host software to the user.

1. Sequential Write 2. Sequential Read 3. Direct Read Use Key, Logical Identifier or Relative Record Number 4.4.1 Sequential Write The host software access method in write mode allows the user to sequentially write data to the file.
The user gives a logical record to the write mode that performs the following functions.

1. Assign an appropriate logical identifier to each physical block.

2. If the file to be written is a keyed file, check the records so that the ascending key order is maintained.

3. Combine logical records into physical blocks.

4. Assemble and publish the channel program, which writes the physical block to the appropriate optical storage device.

5. Configure the index entry for the band when the data is first written to the band. Configure and issue the required channel program, which writes the entry to the index band and updates the index memory.

6. Allocate more space when the space already allocated for the file is gone.

4.4.2 Sequential Read The host software access method in sequential read mode allows the user to read continuously from the file. Upon request, the next logical record will be returned to the user. The sequential read mode access method serves the following functions.

1. Non-blocking method required to retrieve logical records from physical block reading 2. Assemble and issue a channel program to reconstruct physical blocks in proper sequence.

3. If the entities to be read span multiple platters, install or remove the platters in the proper order.

4.4.3 Direct Read Direct read access is done with a key either LID. Any file can be directly modified by specifying a logical identifier. However, only the keyed files are directly modified using the key. In all direct accesses, the user specifies the search arm to search for logical records. The direct read mode access method accomplishes the following functions:

1. Decide which volume will support the input operation.

2. Assemble and publish the search channel program for the physical block containing the requested logical record.

3. Unblock the physical block and retrieve the logical block.

4.5 Search Function Each 7904 byte block is a variable length block header (B
H). BH is 8 bytes to 72 bytes in length, depending on whether the logical record contained in the block contains a user-supplied key and the length of the key.

If the logical record has a key,
BH contains a key equal to the highest key in the block. When performing a keyed search, the host software provides storage unit logic with the desired key as part of the locating CCW. During a keyless search,
Positioned CCW contains either PID or CID.

During a key or LID search, the hardware searches a fixed length field from the beginning of each block. Depending on the type of search, the loaded logic is divided into appropriate subfields. The final data pattern is compared against the search arm supplied by the host software. The search is performed by the following method.

1. The hardware scans the index memory for the band. The band contains key or LID values less than or equal to the target value.

2. Corresponding band is placed.

3. The search lower limit is set to 1. Search limit is 48
Stipulated in.

4. The median between the upper and lower limits is calculated and the seek positions the corresponding track.

5. The first readable BH is read.

6. If the reading is greater than the target value, set an upper limit equal to this value. If the reading is less than the target value, set a lower limit equal to this value.

7. If the difference between the upper and lower limits is greater than 1, then perform step 4. If the difference is equal to 1, then perform step 8.

8. If present, the desired record must be in either the lower bound or the upper bound.

9. Tracks L and H are read sequentially until a record is defined or a key or LID larger than the target value is defined.

Chapter 5 Performance and Operation 5.1 Introduction Chapter 5 describes the performance characteristics of the optical storage unit and the details of the operation panel.

5.2 Usability and maintainability The following items describe the main usability and maintainability of the optical storage device.

5.2.1 Utilization Utilization is defined as the utilization of machines and the utilization of data.

5.2.1.1 Machine Utilization Since each optical storage unit has its own control electronics, machine utilization is increasing. The failure of the optics control electronics affects only one OSU, rather than a string.

Machine utilization is further enhanced by using the dual path feature. If the 8880 Storage Control Unit director fails, another CPU-to-OSU path is used for a different director.

5.2.1.2 Data availability Online fast response time systems require very high data availability. In the event of OSU failure, data availability can be greatly increased with the customer-exclusible 7440 optical media device. In addition to fast and suitable load / unload times, OMU is lightly [1.95g (4.3lbs)] and easy to operate, reducing operating time.

5.2.2 Maintainability The maintainability program for the optical storage subsystem is as follows.

1. Ease of Access Access to all storage units is via the top or front of the device.

2. Modular Design All parts are field replaceable devices assembled in modular form for easy maintenance.

3. Diagnostics This subsystem is capable of cooperating with local and remote-controlled diagnostic instruments.

5.3 Operator Panel The operator panel (Table 5-1 and Figure 5-1) provides the controls and indicators necessary for the system operator to perform the following functions.

1. Power up / down sequence 2. Load / unload optical medium unit 3. Monitoring memory unit activity Chapter 6 Error Recovery 6.1 Introduction Under normal conditions, the error recovery function includes the 8880 / optical storage unit (optical staging unit, hereinafter referred to as the optical staging unit) and / or the operation called by the system. There is. Recovery behavior will vary depending on the system configuration.

6.2 Errors Data errors are errors in the bit pattern read from the platter. The errors result from defects on the platter surface, transient electronic noise, media noise or focusing or tracking errors. The largest source of error is due to media defects.

6.3 Dynamic Defect Skipping The Optical Strange Unit utilizes Dynamic Defect Skipping (DDS) to remove the largest source of error in the data. When a data error occurs during writing to the optical platter, it is immediately detected by using the read back check beam (RBC) and the erroneous data is rewritten.
As a result, all the data written is correct.

6.4 Data Error Correction Error detection (Chapter 2) and correction information is added to each block of data by Optical Device Control (ODC) when it is written to the platter.
When the recorded content is read, the error correction information corrects the data to detect errors that may currently exist and, if possible, correct the data. The error information is coded to check if it is valid for all the data generated by the pre-defined set of rules and written in the recorded block.

An error correction code (ECC) generated by ODC (Optical Device Control, hereinafter referred to as ODC) corrects one of the following error conditions.

1. A single error burst contained within 192 bytes.

2. Double error burst if the total length of bytes including error burst does not exceed 128.

3. If the total length of bytes containing error bursts does not exceed 96, and the distance between any three bursts is not a multiple of 32, then for any combination of 96 independent error bursts, the interval between each burst is 1 Bytes to 95 bytes.

4. If the distance between 3 error bursts is a multiple of 32 bytes, then there are only 3 error bursts, each burst scan being 1 to 32 bytes.

Errors that can be corrected by the error correction code are EEC
It is called a correctable error. ODC hardware corrects ongoing errors by the 2-data block latency required to start the read sequence. The host cannot find a correctable ECC error. The count of correctable errors and the number of bytes read are kept by the optical strange unit and can be read by the host if it is desired to monitor the error rate. .

If a data error is detected and the data cannot be corrected by ECC, Optical Storage Unit 8880
Uses a repeat channel command to read the data accurately. In many cases even the first attempt to read the data will not work, and subsequent attempts made while the accessor and focus are out of position will result in correctable errors in the ECC. Become.
The optical storage unit 8880 signals an uncorrectable error only after all repeated attempts have failed.

6.5 Error Handling Table 6-1 and Error Status Table show the structure of the read bits set by the storage director at read bytes 0, 1 and 2. (The read bytes are described in detail in Description B.) Each configuration requires a specific error recovery operation (Table 6-2) invoked by the system on which the host operates.

Description A Channel command Description B Sense Byte B.1 Overview The Sense Byte represents the state of the optical storage device and the storage director, and consists of 24 bytes and 7 formats.

B.2 Explanation The first 8 bytes (0 to 7) consist of high level sensor and status data. The contents of sense bytes 3 to 6 change depending on the format, but 0
~ 2 does not change (has no format).

The sense byte 7 is a byte for identifying a format of 8 to 23 and a message. The first 4 bits define the format, and the remaining 4 bits define the message. Formats 0,2,3 define Storage Director errors. Format 1 is the state of the storage device,
Format 6 indicates the state of the storage device and the storage director. Formats 4 and 5 are reserved.

Table B-1 is a summary of the sense bytes, and Tables B-2-8 are the details. Tables B-9 to 23 show sense byte 7
Shows the message and format.

Table 9 Interface Requirements 9.1 Introduction This chapter describes the interface requirements between the channel and the 8880 and the interface requirements between the 8880 and the optical storage unit. List signal line and cable requirements.

9.2 Channel Interface The hardware of the Channel Interface provides communication between the 8880 Storage Director and the eight channels. Interfaces are provided in two areas of the storage director, the microcontroller and the data path.

18 inbound signals from the channel, 360/37
There are 19 outbound signals generated by Type 0 line drivers. Table 9-1 describes the channel interface lines as a table.

9.3 Control Interface The control interface (abbreviated as CTL-I) provides a common logical and physical connection between the 8880 storage controller and the optical storage unit. The CTL-I consists of a series of optical storage units (one from 8
It carries 36 signals (Table 9-2) in a daisy chain configuration such as mounting to one unit). Each optical storage unit has dual path capability, thereby allowing control of each unit to be shared between two 8880 storage directors via two separate CTL-Is.

9.3.1 Communication The storage director and each switch interface are CTL.
It is attached in parallel to the -I signal line and allows simultaneous addressing or polling of the optical storage unit by 8880. The output signals from all switch interfaces attached to the same CTL-I are OR'ed together with the input to the storage director on the common signal line. The protocol for this communication is based on polling and selecting and must be initiated by the storage director. The optical storage unit can request a communication unit by the unselected alert line.

9.3.2 Dual Pass Operation The storage unit communicates with the two separate control interfaces via the Dual Pass switch. Dual-path switches can be selected by one interface or placed in a neutral position when the other is busy, and can be used as either interface for interrupt polling or selecting. it can.
The storage director can select one of eight storage units to be connected to CTL-I via the dual path switch at a time. The selected storage unit remains connected to CTL-I until a disconnect command is issued by the storage director.

9.4 Interface cables Table 9-3 lists the external cable requirements for the channel interface and the control interface.

Although the present invention has been described above with reference to the preferred embodiments, the present invention does not violate the spirit and scope of the invention and is not limited by the scope of the claims, and various modifications and changes are possible. However, it is clear that it can be implemented.

[Brief description of drawings]

FIG. 1 is a simplified block diagram of an optical storage system according to the present invention, optionally associated with a magnetic storage device, and FIG. 2 is selectively associated with a number of magnetic disk storage devices, and FIG. 3 shows a state associated with a large number of optical disk units. FIG. 3 is a block diagram of the storage system in FIG. 1, and FIG. 3 shows a plurality of host computers for controlling a plurality of common optical disk units. A simplified block diagram of the modified optical storage system according to the present invention used, FIG. 4 shows control electronics [optical element controller (OD
FIG. 5 is a perspective view showing an arrangement of bands, tracks, sectors and blocks in a platter of an optical storage subsystem. FIG. 6 is a diagram showing a physical data block. FIG. 7 is a diagram showing an operator panel. (10) Host CPU (11) Optical disk unit (ODU) (12) Channel, (13) Control unit (14) (19) Storage director, (15) OPSAM (16) (17) code, (20) Magnetic disk Unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Giuan A Rodriguez, USA 80301 Boulder Navazio Place 4517 (56) References JP-A-56-22171 (JP, A) JP-A-58-129680 (JP, JP, A) A)

Claims (3)

[Claims] 1. A mass storage device having an optical disk unit, a magnetic storage device having a plurality of magnetic disk units, a disk operating system for use with the magnetic storage device, and a disk operating system and a mass storage device. The host / CPU connected to the magnetic storage device and the mass storage device, which has the host resident software that configures the interface between the optical disk units, the channel connected to the host CPU, and the storage director connected to the channel And a plurality of internal microprocessors in the optical disk unit, a storage unit resident software provided in the optical disk unit for receiving signals from channels and giving assembly language commands to the plurality of internal microprocessors. The storage director has control resident software, which receives signals from channels when the host CPU uses the optical disk unit to control the optical disk unit. The optical disk unit is host resident software or control resident software. And an optical storage system which is controlled depending on the storage unit resident software. 2. A magnetic storage device having a magnetic disk unit, a mass storage device having an optical disk unit, and a disk operating system for use with the magnetic storage device, and an optical disk of the disk operating system and the mass storage device. A host / CPU connected to the magnetic disk unit storage device and the optical disk unit storage device, a host / CPU connected to the magnetic disk unit storage device and an optical disk unit storage device, a channel connected to the host CPU, and a first connected to the channel Memory Director and Second
A storage unit having a storage director, a plurality of internal microprocessors provided in the optical disk unit, and a storage provided in the optical disk unit for receiving signals from channels and giving assembly language commands to the plurality of internal microprocessors. Unit resident software, the first storage director receives a signal from the channel by the host CPU when the magnetic disk unit is used, and the first storage director controls the magnetic storage device independently of the host resident software. A second storage director has control resident software,
When the mass storage device is used by the host / CPU, it receives a signal from the channel to control the optical disk unit, and the optical disk unit is controlled depending on the host resident software, the control resident software and the storage unit resident software. Characteristic optical storage system. 3. A disk operating system for use with a magnetic storage device having a plurality of magnetic disk units.
A data transmission method for transmitting data between a host CPU having a system and an optical disk unit having an internal microprocessor via a control unit having a storage director and a channel, the host CPU, the optical disk unit and the control Confirm the data in the host / CPU as the data to be written in the optical disk unit or the data to be read from the optical disk unit, and the process of providing the host resident software, the storage unit resident software and the control resident software in the storage director of the unit Use the control resident software to coordinate the above-identified data with the optical disc unit through the channel or the channel and the data read from the optical disc unit with the host / CPU through the channel. The process of converting the confirmed data or the data read from the optical disk unit in the control unit, and guiding the control signal in the storage director to control the optical disk unit and responding to the control signal from the storage director, the optical disk unit A data transmission method including the step of reading or converting data from the optical disc unit through an internal microprocessor in the optical disc unit and writing the data into the optical disc unit.