JPH0448250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to digital data storage, and more particularly to improved systems and methods for managing and allocating data in disk storage.

One of the primary considerations in the configuration and operation of digital data systems is to store and store information received from a computer's central processing unit (CPU).
In addition, it is necessary to provide an appropriate device that provides appropriate information to the CPU when necessary.

In general, magnetic tape and disk storage systems both have different and unique functional characteristics. Accordingly, each type of storage medium is particularly well suited for some applications, but not for others. Data stored on magnetic tape is arranged in a bit-serial format in a file. That is, since multiple files are stored sequentially on the tape, in order to access a particular file, the magnetic tape must be reeled until the beginning of the requested file is located at the read/write head of the tape device. must be sent to the spool reel. Since the data in this requested file is organized serially in bits or bytes, the requested file must be read or written in bits or bytes from the magnetic tape to locate the portion of the file to be read or written. Must be read out continuously in units.

Thus, serially organized data is advantageously read from and written to tape in succession. And tape is an economical medium for storing data. Additionally, data is written to tape until the complete contents of the file are stored on tape. And the next file is
To use the tape's maximum storage capacity, it is written immediately after the end of the previously written file.

However, since it is impractical to attempt to read from or write to a tape from two or more datasets simultaneously, the serial nature of tape data storage allows the user to store only a single file on each reel of tape. .

Therefore, approximately 90% of all tapes contain only one data set, which is not an efficient use of the tape's storage capacity. Additionally, the tape must be manually loaded into the tape device;
Tape search time increases for each data set stored on tape.

In contrast to this serial file configuration, disk drives provide random access in which all data can be accessed directly by the disk drive's read/write head without requiring serial reading of the entire file or successive files. Data is stored by a method. Furthermore, since the data is stored on disk in a random access format,
A disk device has the advantage that multiple host computers can simultaneously retrieve data from the disk device. Concurrent data access is not possible with tape devices because of the long time required to reposition a magnetic tape to retrieve information from other files stored on it.

However, disk drives are considerably more expensive than tape drives and are specifically used for only the data storage portion of the user's needs. Furthermore, only approximately 75% of the expected storage space of a disk drive is available for data storage purposes since space is required to support read/write operations such as data logging. has been proven.
A disk device stores data in a predetermined block size. Therefore, unless the data file to be stored is equal to the block size,
Storage capacity is wasted on disk. Utilizing this storage capacity under the additional conditions reduces the actual memory used to approximately 50% of the normal capacity of the disk device.

There are several serially organized files, such as a set of program instructions, one instruction being executed consecutively at the same time. There are also other files, such as databases of information (eg, employee directories), where the information is accessed randomly.

Files arranged in series are most compatible with magnetic tape formats. This is because both the file and the magnetic tape are essentially serial. Files containing randomly collected information are most suitable for disk devices that access information on a random access basis.

However, it would be beneficial to provide a storage system that has the data storage space efficiency of a tape device and the data retrieval speed of a disk device.

OBJECTS OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved data storage system for digital computers and the like.

Another object of the present invention is to provide a system and method for storing and accessing serially arranged data more quickly than state of the art magnetic tape data storage systems.

Still another object of the present invention is to provide a storage system that responds to commands from a host system using a tape drive method but utilizes the quick access capabilities of a disk storage device.

Another object of the present invention is to provide a data processing management system that accepts and transmits data from a host computer in serial format while storing and retrieving information from disk storage in random access format.

SUMMARY OF THE INVENTION In summary, according to one aspect of the invention, the foregoing objects of the invention are achieved by providing a "virtual storage system" which is configured to receive and transmit information in serial tape format. a first data buffer in said upper interface for temporarily storing data received from or sent to said upper interface; Become. A plurality of disk storage devices are also provided with a disk storage interface and an associated second data buffer for temporarily storing data sent to and received from the disk storage devices. The interface stages are coupled together and in common with a large main memory that receives and waits for information to flow from one interface to another. Finally, a master control processor is coupled to the interface device and main memory and directs the operation of the device such that the upper interface stage responds to the upper computer in a manner similar to a tape system, but not the disk interface stage. reads and writes data to and from disk storage randomly according to the storage space available at the time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS While the text is prefaced with claims particularly pointing out and distinctly defining the subject matter regarded as the invention, the invention lies in the following description of preferred embodiments, illustrated in conjunction with the accompanying drawings. I think it will be better understood from this point of view.

Figure 1 shows the host computer 1 in a simplified form.
1 shows the basic architecture of the virtual storage system of the present invention when coupled to 0; The present invention
Control one or more very fast and accessible disk storage devices to accept and respond to data just like a tape device, making better use of the available storage, thereby making tape or disk It constitutes a device which has the effect of providing a much wider extended storage capacity and a much faster response time than either. Upper computer 10
Because of the economical operation of the invention, it is intended for use with large body host computers such as the IBM System 360, System 370, and IBM Models 3031, 3032, and 3033 processor complexes. Yes, but any type is fine. The virtual storage system of the present invention can also be used with multiple host computers. The storage system consists of a series of upper interface stages 12a to 12n, the number of interface stages depending on the amount of data to be sent.
Since the upper interface stages are the same, the actual number of stages used is not important for purposes of the present invention. The upper level interface stage is coupled to the upper level computer 10 by a channel 14, which is well known in the art, and transmits information to the computer 10 in the conventional serial format associated with tape drives.

One or more disk interface stages 16
a through 16n are provided and are coupled to all upper interface stages by a common information bus 18.
In this way, information can be transferred between any higher level interface stage and the disk interface stage.

A disk interface stage is respectively coupled to each of disk storage devices 20a-20n. As discussed in more detail, each disk interface stage includes a storage interface, a data buffer, and a local microprocessor controller for operating the disk interface as well as each element of the interface stage.

A main storage device 22 is also connected to the main bus 18 . Memory 22 forms a repository for information flowing from the upper interface stage to the disk interface stage and is also connected to the main bus 18.
2. Acts as a memory for a control processor 24 coupled to. A control processor 24, which is the central processing unit or CPU of the virtual storage system, is coupled to the upper level interface 12 and the disk interface stage, respectively, so that information is received, queued, configured, and stored in the conventional manner. command its operation. The control processor 24 further includes:
It instructs the various upper level interface stages 12 to respond to the upper level computer 10 in a manner that simulates a tape device.

Referring now to FIG. 2, the configuration of exemplary elements of the system will be described in further detail. Processor 2
4 is directly coupled to the upper interface stage 12 and in particular to an internal interface 26 which facilitates the transfer of signals between the control processor 24 and the microprocessor 28 forming the controller for the upper interface stage. The upper interface stage is composed of a data buffer 30 and a data buffer connected to the upper computer 1.
Upper interface 32 that can be shared with 0
and a storage interface 34 through which a data buffer communicates with data bus 18.

The function of the upper level interface stage 12 is to simulate the tape drive system for the upper level computer, that is, to convert the commands of the upper level computer 10 for the tape device into commands for the virtual storage system of the present invention, and to convert the commands of the upper level computer 10 to the tape device into commands for the virtual storage system of the present invention, and to convert the instructions in the form sent by the tape device. This is to send data to the host computer 10. Additionally, the upper level interface stage 12 receives signals from a higher level computer 10 of the type used to operate the tape device. Such signals are obtained by coupling the upper interface stage to multiple bytes, or multiple blocks, or selector channels of the upper computer 10. These cases are seen to include operator commands such as "load tape,""unloadtape," and machine language such as "read,""write," and "forward space file." The upper interface stage responds to both types of signals as if it were an operator and a tape device, acknowledges the signals, responds that the virtual tape reel has been "loaded," and so on.

The data buffer 30 of each higher level interface stage accepts data from the higher level computer 10 in serial form, typically 9 bits in parallel, in a precise manner for feeding back to the tape system for writing onto tape. Buffer 30 de-serializes the information during write operations, ie, stores it in parallel fields that hold individual bits until all eight bytes are available. Generally, 72 bits are sent at a time, thus reducing transmission time. In this way, a compression of up to 90% of the time required to transmit data over line 18 is possible. When data is to be exchanged between buffer 30 and bus 18, the data is transferred to storage interface 34 again in eight parallel bytes so that a very fast exchange of data occurs.
flows. The size of the buffer can vary widely depending on system requirements, but in the preferred embodiment is 64,000 bytes, which is large enough to hold all records to facilitate time sharing of bus 18.

Finally, the data received from the host computer 10 is sent to one or more disk devices 20a to 2.
0n is written on the magnetic disk loaded. Disk interface stage 16 is data bus 1
8 is coupled to a disk drive 20 (not shown) and comprises a local microprocessor controller 36 which operates each element of the interface stage according to instructions from the control processor 24. As with upper interface stage 12, disk interface stage 16 routes instructions from the control processor via interface 38 to local controller 36. At this time, the latter has a data buffer 40 and a disk interface 42.
and the storage interface 44 responds by moving data to and from the disk device.

In particular, storage interface 44 receives eight channels of data from bus 18 and serves to serialize the data for incorporation into buffer 40 in one bit stream.
Configuration and standby of the buffer storage device is ensured by the local controller 36, as is the action of the disk interface 42 which directs data from the buffer 40 to the disk device at the appropriate times.
Furthermore, the disk interface stage is operative to locate and record data on each disk of the associated disk device so that the information can be retrieved when needed.

Data is stored in main memory 22 while the data is in host interface 12 and is received at disk interface 16. High speed main memory 22 thus acts as a "bank" that holds data until one of the disk drives 20 is ready to receive the data. When this condition occurs, the disk interface stage 42 associated with the disk device 20 signals the control processor 24 of its availability. Control processor 24 then directs the main memory or cache 2 to release the data via bus 18 to disk interface stage 42.
Command 2.

Similarly, while the host computer 10 is searching for data, the identity of the data being searched is sent to the control processor 24 via the host interface stage 12;
The processor then determines whether the requested data has already been moved to main memory. If not, the control processor 24 also provides a "transmitter" signal to the disk interface, and the internal control controller 36 transmits the signal from the associated buffer 40 to the data bus 18 via the associated storage interface 44. Furthermore, the data is read to the main storage device 22.

At the same time, available upper interface stage 1
2's local controller 28 enables the associated storage interface 34 so that newly read data is received from the main memory 22 and transferred to the upper interface data buffer 30.
gated to. On the other hand, if so, the data is immediately gated out of the buffer 30, serialized by the host interface module 32, and sent to the host computer 10.

In alternative embodiments, host buffer 30 and disk buffer 40 can be omitted, and their functions are then performed by main memory 22.

In this manner, segments of data distributed across multiple disk drives are compiled, queued, and then automatically reassembled into serial form. Therefore, the information flowing from each disk device 20 to the host computer 10 appears in serial form, just as if it were being read from tape.

As previously mentioned, the high speed main memory provides a cache from which data is selected and held for later reassembly into serial form before being sent to the host computer.

As will be apparent to those skilled in the art who have been trained in the teachings of the present invention, the elements of the virtual storage system can be assembled from commercially available elements and coupled together in any suitable manner. For example, although all of the elements of disk interface stage 16 are shown as being located in one location remote from control processor 24, in reality these elements may be located elsewhere and as appropriate. They can be coupled by cables, buses, etc. The local microprocessor controller 24 used to operate the components of each interface stage may be of somewhat limited capability and may be constructed from any high speed microprocessor available on the market. An example of such a microprocessor is an LSI commercially available from DEC Corporation of Boston, Massachusetts, USA.
-11 or any suitable device that can be assembled from AMD's 2900 series parts. Similarly, the upper interface 12 and the disk interface 12 that convert information into serial and non-serial formats
Interface 16 may be a standard device such as a Model 370 block multiplexer available from IBM Corporation of Armonk, New York. Similarly, IBM block multiplexers can be used for direct storage access, and the actual connections of each device will be well understood by those skilled in the art.

Similarly, buffers 30 and 40 used for temporary storage of data in upper interface stage 12 and disk interface stage 16 may be of any suitable type, although in this embodiment preferably at least 64K bytes of memory. That's fine. One of the commercially available buffers of this type is
It is manufactured by Fairchild Semiconductors and is an N-MOS random access memory with a speed of 200 nanoseconds.

The high speed memory 22 acting as a data cutter must be of a type called a fast access memory, ie, having a cycle time of 400 nanoseconds or less. In a preferred embodiment, the high speed cutlet has a capacity of 16 megabytes. One commercially available memory suitable for use in the present invention is manufactured by Intersil, Inc., Sunnyvale, California, USA, and is manufactured by Storage Corporation, Lewisville, Colorado, USA, the assignee of this application.
Model 3758 marketed by Technology
and 3768.

FIG. 3 is a functional diagram illustrating the operation of the system of the present invention in a "read" mode in which host computer 10 requests information from memory. Control signals are shown by solid lines and data flow is shown by dotted lines. Thus, the host computer 10 generates a command signal to a human operator requesting certain information (e.g., "Load Tape N") and informs the host computer 10 that the data is stored on the tape in serial form. As such, an initial identification or "label" need only be specified. Other elements of the virtual storage system, particularly control processor 24, respond to the information by accessing all data responsive to the requested information and assembling this data into serial form.

In this manner, the host computer 10 recalls a tape N that it assumes contains a particular data set, according to information provided by the individual programs running on this computer. In fact, according to the virtual storage system of the present invention, this particular set of data may be scattered across many different disks and/or located in many locations on a single disk. Therefore, the virtual storage system of the present invention searches within its own memory for data indicating the location where each part of the record designated by the host computer as "Tape N" is stored. Load N.”
respond to operator commands such as in this way,
The system's response is not to instruct the operator to load Tape N, but simply to reread from its memory information about the location of the data set identified as "Tape N."

When the upper level interface stage 12 indicates that the command "Load tape N" has been completed, although this is actually instantaneous compared to the actual loading of the tape, the higher level computer 10 outputs a command to interface 12 indicating a particular match of the block of information to be read to interface 12. This command is sent directly by the upper interface stage 12 to the control processor 24 which identifies each memory location in which information is stored. This can be implemented through the use of a data storage device 46 coupled to the control process. In this embodiment, the data recording device 46 is a random access system in which the location of each sub-block of data that together constitute the data requested by the host computer 10 is recorded.
Memory (RAM) (which can be ``backed up'' by a tape drive and associated tape in case of memory loss in RAM).

When the location of each sub-block of data is identified to control processor 24, a signal is provided to the controller portion of each disk interface stage 36 at which time data is accessed from each disk storage device 20. At this time, the data is read into the buffer 40 of the interface stage 16,
The main memory cache 22 is used for temporary storage until needed by each upper interface stage 12.
prepared for transmission to.

When buffer 40 is filled with data, a signal is output from disk interface stage 16 to control processor 24 indicating this fact, and control processor 24 then forwards the buffered information to high speed main storage cache 22. Send directly to previously allocated space.

For prior art tape systems, the initial "load" operation typically takes about 30 seconds to 5 minutes. Depending on the characteristics of the individual device and, of course, the length of the recording to be read, the total time required to execute a "read" command varies within the range of 1 to 10 milliseconds. In the virtual storage system example of the preferred embodiment, a "load" operation typically takes less than one second. The actual "read" operation generally depends on the length of the record and the cutoff 22, as described above.
It takes 1 to 10 milliseconds depending on the characteristics of The information read at this time is therefore very quickly put into the cutter 22 where it is stored until a signal from the storage interface 12 indicates to the cutter that the upper computer is ready to receive the data. . At this point, data is generated from each point on each disk 20 where it is stored;
They are recorded in serial format in the proper order and prepared to be read into the host computer 10 without any delay in address time or retrieval of the information on each disk. It is therefore clear that the storage system of the present invention has significant time advantages over disks and no loading time delays compared to tape systems. Thus, the ``anticipated buffering effect'' of using Katsushie combines the advantages of disk and tape; in this respect Katsushie combines the elimination of loading in the case of disk with the serial format of tape, thus making data This saves time on the host computer by configuring it completely within the computer. At the same time, because of the excellent organization and cooperation of each component, very little of the real storage space of the desk is used for directing read/write operations or for maintaining or recording data on tape; The area is sometimes called the "overhead". Therefore, a very large percentage of the actual disk memory is available for data. In this way, the storage efficiency of disk memory can be updated to the same level as that of tape.

In the higher-level "write mode" shown in Figure 4, the direction of the procedure and the "reading" mode described above are
The direction is almost the opposite of the mode. As in FIG. 3, control signals are shown as solid lines and data flow is shown as dotted lines. When the host computer 10 signals a request to "write" or record data using conventional tape drive code, this command is sent via the interface stage 12 to the control processor 24. The processor instructs the interface 12 to confirm this command and interrogates the disk interface stage 16 to find a buffer 40 that will accept some or all of the data. Once such locations are determined, these locations are controlled by the control processor 24 on the data recording device 4.
6 is recorded.

At this time, the control processor 24 accepts data from the host computer 10 to the host interface stage 12 and transfers the data to the host interface stage 12.
2 to an appropriate location in the data buffer 30. The space that buffer 30 corresponds to is buffer 40 on the disk interface stage.
If it is to be filled before it can be used, the command ``Allocate Space'' is sent by the control processor to the cache memory 22, after which data from the buffer of the upper interface stage is provided to the cache memory 22. Thereafter, when sufficient buffer capacity is available in one or more disk interface stages 16, the control processor directs the cache memory 22 to buffer the appropriate disk interface stages for filling the disks of the associated disk unit 20. Commands buffer 16 to provide the stored data.

When each book of data is provided by the host computer 10 to the host interface 32,
The storage interface module 34 determines where newly received information is to be stored within the associated buffer 30, compresses the data into a serial format, yielding, for example, eight channels of data, and identifies the information block. Add bit(s) to indicate the size of this block. in this way,
Data is continuously sent to buffer 30 until a data block is filled or the host computer generates a signal indicating the end of a recording. According to an important feature of the invention, such a signal is interpreted by the local controller 28 as the end of a message signal from which no further allocation of buffer storage space is required.

At this time, the control processor 24 transfers the data stored in the data buffer 30 to the high-speed cutter 2.
Send to 2. As mentioned above, while the host computer is storing data in the data buffer 30, the control processor 24 can "search" for sufficient space on the disk device 20, and use this space to store data in the data buffer 30 at this time.ゝCan be assigned to certain data. Thus, when the end of recording signal is received within the control processor, the data can be serialized and sent to the high speed cutter and then to the disk drive 20 for storage.

In other words, when the host computer issues an initial "load tape" command (i.e., instructing the operator to provide an empty tape for data storage), this command is passed through the host interface stage 12. and sent to the control processor 24.
This control processor 24 controls one or more disks 2
0 and responds to the command ``Load Tape'' by searching for space at 0 and reserving sufficient space in one or more of the buffers 30 of the disk interface stage. Once this is complete, control processor 24 instructs host interface stage 12 to receive the data from host computer 10, deserialize it, and store it in the associated buffer 30. Once this buffer is filled and no more buffer space is available, this data is sent to the cutter memory 22. Enough disk space
When space is available, the next step is to send the disk control interface 4 of the disk interface stage 16 to the control processor 24.
2 instructs the associated disk device 20 to write data, after which the interface module 44 reads this information, serializes it, and places it into its associated buffer 40, where this information is Written to the associated disk 20. Further, the data storage system of the present invention can operate simultaneously with a general tape device for backup. Many computers maintain duplicate copies of data for reliability, and the system of the present invention can be used as the primary data storage system, while a typical tape device is stored on the disk device of the system. It can be operated simultaneously with the present invention to store copies or backups of data collected. Therefore, the basic data storage medium, i.e., the disk device of the present invention, provides high-speed data retrieval, while the tape device allows data to be retrieved even if the data stored in the disk device is damaged for some reason. Give additional copies.

Those skilled in the art will appreciate that the combination of the advantages of prior art tape and disk drive systems is possible by associating a high speed cutter with a control processor, along with upper interface and disk interface stages and associated control modules. That is, the easy access capability of a disk device is combined with the storage efficiency of a tape device, and through the mediation of the present invention, a disk device can manage a central processing unit like a tape device without having the drawbacks of a tape device. It will be clear that an efficient "virtual memory system" is obtained. Since the memory disk is permanently attached according to the present invention, no operator intervention is required when searching a tape-type record (i.e., a sequential record). Furthermore, prior art disk devices can be used without modification with the virtual storage system of the present invention, i.e., the inventive system does not require any device or interface inserted between the prior art host computer and the prior art disk device. He can be considered an ace. Therefore, there is no need to modify the disk device or the host computer in order to enable them to operate in conjunction with the virtual storage system of the present invention.

Furthermore, the virtual storage system of the present invention can be used to interface between multiple host computers and multiple disk devices. Therefore, if an operator operates one or more host computers and a limited number of disk devices, the virtual storage system of the present invention can achieve maximum storage efficiency and avoid undue duplication of disk or tape storage systems. It will be seen that it can be used to eliminate. The host interface installation of the present invention can be coupled to one or more host computers. Furthermore, it will be appreciated that the provision of a high speed memory or cutter is essential to the "advance buffering" of the present invention. Since data is stored on various disk drives and must be collected and reformatted before being transferred to a host computer, high-speed memory is required to temporarily store the data as it is collected from the disk drives. is necessary. This collected data is reformatted for transfer to the host computer without delay. By using high-speed cables as intermediate buffers between the host computer interface and each disk device interface stage, multiple data buffering can be achieved, i.e., multiple data locations on multiple disk devices can be achieved according to the invention. (i.e., “randomly formatted data”) is assembled, ordered,
It can be temporarily stored in the high-speed cutter until called up by the host computer. In this way, there is no need for a delay in reading information from memory to the host computer. Similarly, data output from a host computer can be arranged, divided, and stored until such time that each storage area of the disk is available for storage of information.

A particularly important point provided by the storage system of the invention is the possibility of data compression. Until now, the general concept of data compression, which may involve replacing long strings of digital values ``1'' or ``0'' with a symbol denoting the length of this string, was Due to compression, disk drives have not been successful. However, according to the present application, since the disk device is considered as a tape, this problem of the prior art is eliminated, and data compression can be shared with disk-type storage devices. data compression is implemented at the upper interface stage, i.e., during write operations long strings of ``1'' or ``0'' can be detected and replaced with relatively short symbols;
Preferably, during a read operation, these strings are detected and replaced by the data thus defined.

Finally, it should be noted that many other modifications and improvements may be made to the virtual storage system of the present invention, and that the examples presented herein are illustrative only, and that the scope of the invention is within the scope of the appended claims. It will be clear that the invention is to be understood as limited only in scope.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the entire configuration of a virtual storage system configured according to the present invention, FIG. 2 is a diagram showing the flow of control and information signals within the system of FIG. 1,
3 and 4 are diagrams showing the flow of command signals and information in "read" and "write" situations, respectively. 10... Upper computer, 12... Upper interface stage, 14... Channel, 16... Disk interface stage, 18... Common information bus, 20... Disk memory, 22... Main storage device, 24 ... control processor, 26 ... internal interface, 28 ... microprocessor,
30...Data buffer, 32...Upper interface, 34...Memory interface, 3
6... Local controller, 38... Interface, 40... Data buffer, 42... Disk interface, 44... Storage interface, 46... Data recording device.

Claims (1)

[Scope of Claims] 1. A pseudo tape storage device used with at least one host computer, comprising: a cache memory; and at least one host computer interface that connects the at least one host computer and the cache memory. at least one disk storage device for storing data in a random access format; at least one disk storage interface connecting the at least one disk storage device to the cache memory; a tape connected to a higher-level computer interface, the at least one disk storage device interface, and the cache memory, the tape being received by the higher-level interface from the higher-level computer in response to a write command from the higher-level computer; Writing data in a serial format suitable for writing to a storage device in a predetermined area of the disk storage device in a random access format, and reading data stored in the disk storage device in response to a read command from the host computer. and a control device that controls the host computer interface, the disk storage device, and the cache memory so as to assemble the read data into serial data and send it to the host computer, the control device comprising: means for specifying an area within the at least one disk storage device for storing a fixed unit of data received from the at least one upper-level computer; and an upper-level computer address of each fixed unit of data; means for storing data indicating a relationship between the address of the area of the at least one disk storage device used for storing unit data; a fixed unit of data indicating a relationship between the computer address of the selected fixed unit of data and the area in the at least one disk storage device used for storing the selected fixed unit of data; A pseudo tape storage device comprising: means for reading data from at least one disk storage device in a random access format and assembling the read data into serial data. 2. The control device communicates with an operator and at least one
2. A pseudo tape storage device according to claim 1, wherein data is stored and accessed in at least one disk storage device in response to commands received from said higher-level computer. 3. Claim 1, characterized in that it comprises at least one of the host computers, at least one of the disk storage devices, and a data compression device and a data decompression device disposed between them.
Pseudo-tape storage device as described in Section. 4. The pseudo tape storage device according to claim 1, wherein each of the upper computer interfaces includes a data buffer. 5. The pseudo tape storage device according to claim 1, wherein the disk interface includes a data buffer. 6. A pseudo-tape storage method for use with at least one host computer, wherein data is stored on tape between the host computer and a data cache memory including a high-speed main memory through a host interface device associated with each host computer. exchange data in a serial format suitable for writing to the device, and at least one data exchange in a random access format.
storing data in a data storage device; connecting the at least one disk storage device to the data cache memory with at least one disk storage device interface; and receiving information from the at least one host computer. specifying an area in at least one disk storage device for storing fixed units of data in the disk storage device; and specifying an upper computer address of each fixed unit of data and the fixed unit of data. storing data indicating a relationship between the address of the area of the at least one disk storage device used for storing a fixed unit of data selected by the at least one host computer; , using data indicating the relationship between the upper computer address of the selected fixed unit of data and the area in the at least one disk storage device used for storing the selected fixed unit of data. , reading from at least one of the disk storage devices in a random access format, and assembling the read data into serial format data. 7. The pseudo tape storage method according to claim 6, wherein the flow of data between the disk storage device and the data cache memory is controlled by a system controller. 8. storing data in the disk storage device in response to commands received by the system controller from an operator and the host computer;
8. The pseudo tape storage method according to claim 7, wherein the pseudo tape storage method is accessed. 9. Data received in serial form from the host computer by the host computer interface is converted into a non-serial format before being transferred to the cache memory, and the data is processed before being written from the cache memory to the host computer. 7. The pseudo tape storage method according to claim 6, wherein the data is serialized again. 10. The pseudo tape storage method according to claim 6 or 9, wherein the data received from the host computer is compressed before being stored in the disk storage device. 11. The pseudo tape storage method according to claim 6, wherein the address of a storage area where the data is stored in the disk storage device is stored in a random access memory. 12. Claim 1, characterized in that said address is additionally stored in another memory device.
The pseudo tape storage method according to item 1.