JPH05173724A - Magnetic tape storage device - Google Patents

Abstract

PURPOSE:To simplify access to a descriptor concerning a magnetic tape. CONSTITUTION:When a control table is outputted by a host device (host) 20 while instructing the write of the control table such as a volume control table or a file control table concerning the magnetic tape mounted on a magnetic tape storage device 10, an MPU 142 of a magnetic tape storage controller 14 writes the control table in a RAM 141. On the contrary, when the host device 20 instructs the read of the control table for confirming control table contents, the MPU 142 reads the desired control table from the RAM 141 and outputs it to the host device 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape storage device using a magnetic tape as a storage medium, and particularly for easily accessing the descriptor when the host device manages the magnetic tape with the descriptor. A preferred magnetic tape storage device.

In a computer system, a magnetic tape storage device has been conventionally used for data backup of a magnetic disk device. This magnetic tape storage device has a feature that a large amount of data can be stored for a long time by using a magnetic tape (called a volume) having a large storage capacity as a storage medium. In a magnetic tape storage device, usually, a large number of magnetic tapes are exchanged and used, and a plurality of data are stored in a single magnetic tape in units of files, or one file is spread over a plurality of magnetic tapes. In many cases, they are stored after being stored. For this reason, a host device (host) that operates the magnetic tape storage device manages the magnetic tape by using descriptors such as a volume control label and a file control label.

The host device uses the descriptor as a clue to give an instruction to the magnetic tape storage device to record data on the magnetic tape or read desired data from the magnetic tape. Therefore, how to efficiently access the descriptor of the host device is extremely important for improving the operating efficiency of the magnetic tape storage device, and thus the operating efficiency of the entire computer system. The present invention has been made in response to such a request, and particularly, simplifies access to a descriptor of a higher-level device.

[0004]

2. Description of the Related Art There is a magnetic tape storage device in which a magnetic tape having an extremely large storage capacity is used as a storage medium so that it can be used for backup of a magnetic disk device. In this magnetic tape storage device, since a large number of magnetic tapes are used by being exchanged, it is necessary to distinguish each magnetic tape by some method, and a plurality of data is stored in one magnetic tape in units of files. If it is done (multi-file reel), it is necessary to distinguish each file by some method. Further, if one file is stored over a plurality of magnetic tapes (multi-reel file), it is also done by some method. Need to identify. A magnetic tape is read and written with two types of data blocks and special records that represent delimiters called tape marks. To enable the above-mentioned distinction and identification, a data block of a predetermined portion of the magnetic tape is used to create a volume. The descriptors of the control label and the file control label are stored so that the host device can manage the magnetic tape by these descriptors.

The format for storing the descriptor on the magnetic tape is as follows.
There are standard label format, non-standard label format, and other non-label format without descriptor. Generally, FIG.
The standard label format shown in 1 is used. However, in FIG.
1 is an example of a multi-file reel and a multi-reel file. A physical BOT is provided at the head of each magnetic tape, and a physical EOT is provided at the end of the first and middle magnetic tapes.
HDR1, HDR2 and EOF1, EOF2 as file control labels (however, with tape marks TM before and after the data block of the actual data forming the file,
For the last file on the first and middle magnetic tape, EOV1, E, which indicates that the file continues on the next magnetic tape.
OV2) is stored, and VOL1 as a volume control label is stored next to the physical BOT. The logical EOT is also stored at the last position of the data block of the last file of the first and intermediate magnetic tapes.

The specific contents of the volume control label and the file control label are as shown in FIG. 12, of which the label identification numbers are VOL1, HDR1, HDR2, EOF.
1, EOF2, EOV1, EOV2 are represented. The volume serial number is the unique number of each magnetic tape, the file serial number is the unique number of each file, the file identification number is the file name number, the volume order is the reel order of a multi-reel file, the file order is the file order of a multi-file reel, and the block. The count indicates the number of blocks contained in the file. The other items are publicly known and therefore omitted. The upper device instructs the magnetic tape storage device,
While giving the descriptors and data, the descriptors and data are recorded on the magnetic tape, and if necessary, the magnetic tape storage device is instructed to read the descriptors and data from the magnetic tape.

FIG. 13 and FIG. 14 each show an example of access to a descriptor made by a higher-level device.
2 shows the initialization processing in the standard label format for the new magnetic tape, and FIG. 13 shows the initialization processing of the header label in the standard label format when the output file is opened. However, the double frame represents tape motion. In FIG. 13, when a new magnetic tape is mounted on the magnetic tape storage device (step 101), the magnetic tape is physically controlled by the physical control of the magnetic tape storage device.
Positioned at OT (step 102). In this state, the host device issues a write command and VO
The contents of L1 are given to the magnetic tape storage device, and the magnetic tape storage device uses VOL1 after the physical BOT of the magnetic tape.
Is written (step 103), and then an ERASE command is given to provide an erase pattern (non-recording portion) next to VOL1 (step 104). And again,
The write command and the contents of HDR1 are given to the magnetic tape storage device, and the VO of the magnetic tape is sent by the magnetic tape storage device.
HDR1 is written next to L1 (step 10
5). Finally, give TM command and then TM after HDR1.
Is written (step 106).

In FIG. 14, the magnetic tape is a physical BO.
Assuming that the device is positioned after T, the host device issues a read command to cause the magnetic tape storage device to read VOL1 and HDR1 (old) from the magnetic tape (step 201), and then execute the BACK SPACE command 2 It is issued once and the magnetic tape is returned to the front of VOL1 (step 202). Then, issue the SPACE command once to advance to a position beyond VOL1 (step 20
3) Next, write command and new HDR1 are given to write new HDR1 next to VOL1 (step 204), and then write command and HDR2 are given to write HDR2 next to HDR1 (step 2)
05). Finally, give TM command and then T after HDR2.
M is written (step 206).

FIG. 15 is a flow chart when the host device performs a file search process using a descriptor on a standard label type magnetic tape, and a control label has been stored in advance on the magnetic tape. And After the magnetic tape is mounted and positioned after the physical BOT (step 301), the host device issues a read command to cause the magnetic tape storage device to read the VOL from the magnetic tape.
1 is read (step 302), and the read command is issued again to read the content of the next control label (step 303). Then, if the read content is HDR1 this time (YES in step 304), it is determined whether the file corresponds to the desired file from the file identification number or the like (step 305), and if NO, the SPACE FILE command is executed three times. Issue and EO about files up to that point
The magnetic tape is advanced to the start position of the control label next to F2 (or EOV2) (steps 306 to 30).
8). Then, a read command is issued to read the contents of the next control label (step 303), and if HDR1 it is judged whether or not it corresponds to the desired file (steps 304 and 305). Step 30
The processing from 6 onward is repeated.

If YES in step 305, a read command is issued and the HDR following HDR1 is issued.
2 is read (step 309), the SPACE FILE command is issued once to advance to the position immediately after the tape mark TM immediately after (step 310), and after predetermined search success processing (step 311). , Finish the flow. If NO in step 304, it is determined whether the control label is EOV1 (step 312). If NO, a predetermined search failure process is performed (step 31).
3) When the flow is completed and YES is obtained in step 312, an unload command is given to unload the magnetic tape (step 314), and then step 301
Return to.

In this way, the host device reads the desired data from the magnetic tape by using the descriptor as a clue by storing a predetermined descriptor together with the data on the magnetic tape in advance by using the magnetic tape storage device. It is possible to get it out. Normally, when a host device reads / writes data from / to a magnetic tape storage device, it performs batch processing on a file-by-file basis, and since the data in a file is continuous, it may read / write back and forth within one file. Nothing happens. Since the data amount of each file is relatively large, it is appropriate to place the data on a magnetic tape, which is a storage medium that can be sequentially accessed and has a large storage capacity. The processes shown in FIGS. 13 to 15 are executed by the operation system of the host device controlling the magnetic tape storage device based on the macro instruction.

[0012]

However, in the above-mentioned prior art, since the descriptors such as the volume control label and the file control label are placed at the head portion of the magnetic tape and before and after each file data, the header The host device accesses (reads / writes) the descriptor by processing such as label update, volume open, and file search.
However, there is a problem in that command processing from the host device to the magnetic tape storage device is complicated, there are many tape motions, repositioning frequently occurs, and it takes time to execute the processing. For example, if you want to know the attributes of a file, you have to read the magnetic tape to the file, and for the entire volume, specify the attributes such as the total number of files and whether it is a multi-file reel or a multi-reel file. It was necessary to read through the entire magnetic tape to get it. From the above, an object of the present invention is to provide a magnetic tape storage device that can easily access a descriptor.

[0013]

FIG. 1 illustrates the principle of the present invention. Reference numeral 10 is a magnetic tape storage device using a magnetic tape managed by a control table as a descriptor as a data storage medium, and 12 is a data recording / recording targeting the magnetic tape.
A magnetic tape drive device 14 for reproducing data is controlled by a magnetic tape drive device 14 according to an instruction from a host device to record / reproduce data on / from a magnetic tape or to manage a control table. Is a program ROM storing a control program, 141 is a RAM partially including a control table storage area, and 142 is a RAM according to an instruction of a host device using the control program.
Is an MPU that writes and reads a control table to and from the magnetic tape drive device, and controls the magnetic tape drive device to record and reproduce data on the magnetic tape. 20
Is a higher-level device, which gives instructions to the magnetic tape storage device to write and read data to and from the magnetic tape while managing the magnetic tape using the control table.

[0014]

The MPU 142 outputs the control table when the host device 20 issues an instruction to write the control table, such as a volume control table or a file control table for the magnetic tape mounted on the magnetic tape storage device 10, for new registration or update of the control table. Writes in the control table information storage area of the RAM 141 as a control table of the magnetic tape, and performs new registration or update. In addition, the host device 2
When 0 instructs reading of a desired control table such as confirmation of the contents of the control table such as the volume control table and the file control table regarding the magnetic tape mounted on the magnetic tape storage device 10, the MPU 142 causes the R
A desired control table is read from the control table information storage area of the AM 141 and output to the host device 20.

As a result, when the host device 20 issues an instruction to write or read the control table relating to the magnetic tape mounted on the magnetic tape storage device 10, the MPU 142 on the magnetic tape storage device 10 side makes a random access to the RAM 141 capable of random access. The control table is written and read with the magnetic tape, and no particular operation is performed on the magnetic tape, so there is no tape motion and
Repositioning of the tape does not occur, the access to the control table by the higher-level device 20 is simplified, and the execution time of the access related to the control table is significantly shortened. In many cases, the control table is frequently accessed, but even in such a case, the operating efficiency of the entire system including the host device 20 does not deteriorate.

[0016] The volume control table for the magnetic tape of the multi-reel file includes identification information that the file is a multi-reel file, and the volume control table for the magnetic tape of the multi-file reel includes information about the total number of files in the reel. Then, these information can be obtained by the host device at any time without tape motion. Further, by including the position information on the magnetic tape for each file in the file control table for the magnetic tape of the multi-file reel, it is possible to quickly position the magnetic tape to the desired file.

Physical BO of magnetic tape on which data is stored
When the magnetic tape is unloaded using the area next to T as a storage location, the control table information for the magnetic tape stored in the RAM is saved, and then when the magnetic tape is mounted in the magnetic tape storage device. , Read the control table information from the area next to the physical BOT of the magnetic tape,
Restore to RAM. As a result, it is possible to handle a large number of magnetic tapes only by securing an area for storing a control table for one magnetic tape in the RAM, and it is not necessary to prepare a special storage medium for backup. Further, when the magnetic tape is automatically positioned at the head position when the magnetic tape is mounted, the descriptor information can be quickly restored without any special search.

When the RAM has a high access speed and is volatile, the control table information is backed up by the power source backup device when the power source fails. This makes it possible to prevent the control table information from being lost even if a failure such as a power supply abnormality, a momentary interruption, or a power failure occurs, and prevent adverse effects such as inaccessibility of the magnetic tape.

[0019]

2 is a block diagram of an embodiment of the present invention, in which the same parts as those in FIG. 1 are designated by the same reference numerals. Reference numeral 10 is a magnetic tape storage device that uses a magnetic tape managed by a control table as a descriptor as a data storage medium, 12 is a magnetic tape drive device that records / reproduces data on / from the magnetic tape, and 120 is magnetic. A tape drive 121 is a drive controller that controls the magnetic tape drive according to the instructions of the magnetic tape storage controller to record or reproduce data in a predetermined format. A controller 14 controls the magnetic tape drive according to the instructions of the host device. A magnetic tape storage controller for recording / reproducing data to / from the magnetic tape and managing a control table, and 140 is a program RO storing a control program.
Reference numeral M, 141 is a RAM including a control table information storage area as a part, 142 is a control program for writing and reading a control table to and from the RAM according to an instruction of a host device, and controlling a magnetic tape drive device to perform magnetic recording. MP for recording / reproducing data to / from tape
U and 143 are host interfaces for exchanging commands, control tables, and data with the host device, 14
4 is a DMA controller, 145 is a data buffer, 1
A drive interface 46 sends and receives commands, control tables, and data to and from the magnetic tape drive device.

Program ROM 140, RAM 141,
MPU 142, host interface 143, DMA
The controller 144, the data buffer 145, and the drive interface 146 are connected to the internal bus,
Host interface 143, DMA controller 1
44, the data buffer 145, and the drive interface 146 are connected to the DMA bus. RAM 141
A volatile semiconductor memory having a high access speed is used for reading and writing control table information for the magnetic tape mounted in the magnetic tape drive device 12. Reference numeral 16 denotes a power backup device, which monitors the power supplied to the magnetic tape storage device and, when a power failure such as a power failure, a momentary interruption, or a power failure occurs, backs up the power to the RAM 141 and loses internal information. Prevent. Two
Reference numeral 0 denotes a host device, which gives instructions to the magnetic tape storage device while writing and reading data to and from the magnetic tape while managing the magnetic tape using the control table.

FIG. 3 shows a magnetic tape recording format in the case of a multi-reel file and a multi-file reel in this embodiment. Physical BO at the beginning of each magnetic tape
T, a physical EOT is provided at the end of the first and middle magnetic tapes. A tape mark TM is recorded before and after the data block of the actual data forming the file, and two tape marks TM are recorded after the last file of the last magnetic tape, which indicates the end of the data. Has been done. A logical EOT is also stored in the last position of the data block of the last file of the first and intermediate magnetic tapes. The area a between the physical BOT of each magnetic tape and the logical BOT of the first file is used to back up the control table information for its own magnetic tape. Data and tape marks on the magnetic tape include logical block IDs in ascending order starting from 0 and physical block IDs in ascending order starting from 0 at constant distances. The final position and the start and end positions of each file are managed.

When the magnetic tape is mounted on the magnetic tape storage device 10, the load point is the physical BOT, and the control table information recorded between the physical BOT and the logical BOT is voluntarily controlled by the magnetic tape storage controller 14. It is read and restored in RAM 141, and finally the logical BO
After being positioned at T, the magnetic tape drive device 12
Becomes a ready state and is notified to the higher-level device 20, and the higher-level device 20 is in the area b after the logical BOT.
Only the same format as the conventional unlabeled format can be accessed. Normally, when the logical EOT is detected, the host device 20 finishes writing on the magnetic tape.

The control table information storage area of the RAM 141 stores one volume control table as shown in FIG. 4 and one (in the case of a single file reel) or a plurality of (in the case of a multi file reel) file control table. It The volume control table contains overall management information about the volume. The file control table is provided for each file in the volume, and the file control table includes file management information. Of these, the table identification number (label type) indicates whether the control table is for a volume or a file. Whether the volume includes files that span multiple reels according to the volume characteristics, the total number of files in the volume by the number of files,
Last block ID is the last block position of the volume,
Whether or not the file spans two reels is indicated by the file characteristics, the start block ID represents the start position of the file in the volume, and the end block ID represents the end position of the file in the volume. Then, in the case of the multi-file reel, the file order (file number) indicates which file in the volume. The file order is 1, 2, ... In order from the file on the BOT side of the magnetic tape. The other items are the same as the conventional standard label format, and therefore omitted.

The higher-level device 20 instructs the magnetic tape storage device 10 to write the control table information and data to the RAM 141 and write the control table information to the magnetic tape to store the data on the magnetic tape. If necessary, the magnetic tape storage device 10 is instructed to read the control table information from the RAM 141 and input it, or read the data from the magnetic tape and input it. The upper device 20 accesses the data on the magnetic tape in the same manner as in the conventional unlabeled format. On the other hand, the control table information is accessed using a special extended command. Figure 5 shows the specifications of a specific example of this extended command.
And shown in FIG. In these figures, "CPU" refers to the host device side, and "I / O" refers to the magnetic tape storage device side. The SET LABEL command specifies whether the operation target is the volume control table or the file control table,
Used in the case of the file control table to indicate the file order. RAM14 for READ LABEL command
SET to instruct to read from 1 to upper device 20
It is used in combination with LABEL, and the WRITE LABEL command is used in combination with SET LABEL to instruct writing from the higher-level device 20 to the RAM 141.

7 and 8 each show an example of access to the control table information performed by the higher-level device 20, FIG. 7 shows an initialization process for a new magnetic tape, and FIG. 8 shows a file when a file is opened. The update processing of a control table is shown. In FIG. 7, when a new magnetic tape is mounted on the magnetic tape storage device 10 (step 401), the magnetic tape storage control device 14
The MPU 142 instructs the magnetic tape drive device 12 to load the magnetic tape via the drive interface 146, and causes the magnetic tape drive device 12 to perform the tape loading. Then, the loading is stopped when the physical BOT is detected (step 402). Then, the MPU 142 gives an instruction to read the magnetic tape, causes the magnetic tape drive device 12 to reproduce the control table information stored in the area a in FIG. 3, and clears the control table information storage area of the RAM 141 in advance. Stored in (step 40
3) Since there is no information on the new magnetic tape, the control table information storage area remains cleared.

Then, when the area a ends and the logical BOT is reached, the MPU 142 instructs the tape stop to position the magnetic tape in the logical BOT (step 40).
4). At this point, the magnetic tape drive device 12 becomes ready and the MPU 142 sets the host interface 14
The drive ready state is notified to the higher-level device 20 via 3. In this state, the host device 20 is SET LABEL + WRITE LA
Volume control table information including a BEL command and desired contents is given to the magnetic tape storage device 10 to instruct writing. Command is host interface 14
3 is input to the MPU 142, and the MPU 142 writes the volume control table information input from the higher-level device 20 in the control table information storage area of the RAM 141 according to the command (step 405). Next, the host device 20 gives file control table information (file order 1) consisting of the command SET LABEL + WRITE LABEL and desired contents to the magnetic tape storage device 10 to instruct writing. MPU 142 follows host device 20
File control table information input from the RAM 14
The data is written in the control table information storage area No. 1 (step 406). This completes the initialization process.

In FIG. 8, assuming that the control table information has already been recorded in the area a of the magnetic tape, the magnetic tape is mounted on the magnetic tape storage device 10 (step 501), and the MPU 14 of the magnetic tape storage control device 14 is executed.
Reference numeral 2 instructs the magnetic tape drive device 12 to load the magnetic tape via the drive interface 146 to cause the tape loading. And the physical BO
When T is detected, the loading is stopped (step 502). Then, the MPU 142 gives an instruction to read the magnetic tape, causes the magnetic tape drive device 12 to reproduce the control table information stored in the area a in FIG. 3, and clears the control table information storage area of the RAM 141 in advance. (Step 503). And
When the area a ends and the logical BOT is reached, the MPU 14
2 indicates tape stop, and the magnetic tape is a logical BOT
(Step 504).

In this state, the host device 20 sets SET LABEL +
A READ LABEL command is given to the magnetic tape storage device 10 to instruct reading of the volume control table. The command is MPU via the host interface 143.
142, and the MPU 142 follows the command to R
The volume control table information is read from the control table information storage area of the AM 141 and output to the host device 20 via the host interface 143. Host device 2
0 reads the input volume control table information (step 505). Next, the upper device 20 uses SET LABE
An L + READ LABEL command is given to the magnetic tape storage device 10 to instruct reading of the file control table related to file order 1. MPU 142 that received the command
Reads out the desired file control table information from the control table information storage area of the RAM 141 and outputs it to the host device 20 via the host interface 143. The host device 20 reads the input file control table information (step 506).

Next, the upper device 20 uses SET LABEL + WRITE.
The LABEL command and the file control table information (file order 1) changed to the desired content are given to the magnetic tape storage device 10 to instruct writing. The command is input to the MPU 142 via the host interface 143, and the MPU 142 rewrites the file control table of file order 1 in the control table information storage area of the RAM 141 with the file control table information input from the host device 20 according to the command (step 507). ). As a result, the update processing of the file control table for file order 1 ends. The same applies to the case of performing the update processing for the file order 2 and thereafter. Thus, when the higher-level device 20 accesses the control table information to newly register or update,
It only needs to read and write to the RAM 141 with high access speed, command processing is simple, and there is no tape motion and repositioning does not occur except when the tape is mounted, so processing can be executed in a short time. Also, deterioration of the head is less likely to occur.

FIG. 9 is a flow chart when the magnetic tape storage device 10 performs the unloading process. The MPU 142 of the magnetic tape storage control device 14 instructs the magnetic tape drive device 12 to rewind the magnetic tape via the drive interface 146. Then, it stops when the physical BOT is detected (step 601). Then
The MPU 142 instructs writing on the magnetic tape, reads each control table from the RAM 141, outputs the control table to the magnetic tape drive device 12, and overwrites the control table information in the area a in FIG. 3 to save all the control table information. Tighten (step 602), stop when recording of all control table information is completed,
Instruct REWIND to unload (step 60
3). When the unloading is completed, the magnetic tape can be removed. As a result, the control table information stored in the RAM 141 is saved and backed up at the beginning of the corresponding magnetic tape (nonvolatile storage medium).
Next, when the same magnetic tape is mounted, the control table information is read from the magnetic tape and the RAM 141 is read.
It is possible to restore to, and there is no need to prepare a special storage medium for backup. Further, since the control table information storage area of the RAM 141 is sufficient for one magnetic tape, the load on the memory capacity is small.

FIG. 10 is a flow chart when the host device performs a file search process on the magnetic tape of the multi-file reel by using the control table information. The control table information is already stored in the area a of the magnetic tape in advance. When the magnetic tape is mounted on the magnetic tape storage device 10 (step 701), the control table information stored in the area a is reproduced and stored in the control table information storage area of the RAM 141 (step 70).
2), the magnetic tape is positioned in the logical BOT (step 703). In this state, the higher-level device 20
The L + READ LABEL command is given to the magnetic tape storage device 10 to instruct reading of the volume control table. The command is input to the MPU 142 via the host interface 143, and the MPU 142 reads the volume control table information from the control table information storage area of the RAM 141 according to the command and outputs it to the host device 20 via the host interface 143. The higher-level device 20 reads the input volume control table information (step 704) and registers the number of files in it as FC (step 705).

Next, the upper level device 20 sets the search file order i = 1 (step 706), and then SET LABEL +
A READ LABEL command is given to the magnetic tape storage device 10 to instruct the reading of the file control table related to the file order i. The MPU 142 that received the command is R
The file control table information relating to the desired file order i = 1 is read from the control table information storage area of the AM 141 and output to the host device 20 via the host interface 143. The host device 20 reads the input file control table information (step 707), determines from the file identification number and the like whether it corresponds to the desired file (step 708), and if NO, determines whether i = FC (step 709). If the answer here is NO, i is incremented (step 710) and then step 70
Return to 7 to read the next file control table,
It is determined whether the file is the desired file (step 708). Thereafter, the same processing is repeated, and if YES in step 708, the higher-level device 20 uses the start block ID of the file control table information to instruct the magnetic tape storage device 10 of the location of the head position of the file.

The MPU 142 instructed to the location instructs the magnetic tape drive unit 12 to search-feed the magnetic tape and fast-forwards the block ID of the magnetic tape.
Is monitored, the tape feed is stopped when it matches the desired start block ID (step 711), a search success notification is sent to the host device 20, and the host device 20 performs a predetermined search success process to perform the file search process. Is completed (step 712). On the other hand, if YES in step 709, the previously read file order F
It is judged from the file characteristics of the file control table information related to C whether it is a multi-reel file (step 713),
If YES, the host device 20 instructs the magnetic tape storage device 10 to unload the magnetic tape. The MPU 14 of the magnetic tape storage controller 14 that received the unload instruction
After instructing the magnetic tape drive device 12 to unload, the magnetic tape unloads the magnetic tape (step 71).
4) and returns to step 701. If NO in step 713, the higher-level device 20 performs a predetermined search failure process (step 715).

As described above, in the file search, the control table information read from the magnetic tape is stored in the RAM 141.
After being placed on the upper layer, the higher-level device 20 can determine whether or not the desired file exists only by accessing the control table information of the RAM 141, and when it exists, obtain the position information and copy the magnetic tape. Since it is possible to locate the position at once, it is not necessary to repeat the magnetic tape search operation to access the descriptors of individual files, so that the file search can be completed within a short time. ..

When the host device 20 writes data on the magnetic tape, the data is temporarily stored in the data buffer 145 via the host interface 143 and the DMA controller 144 based on the instruction of the MPU 142, and then based on the instruction of the MPU 142. , Is output to the magnetic tape drive unit 12 via the data buffer 145, the DMA controller 144, and the drive interface 146 and is recorded on the magnetic tape. When the host device 20 reads data from the magnetic tape, the reverse path is used. In addition, when the power supplied to the magnetic tape storage device 10 has a failure such as an abnormality, a momentary interruption, or a power failure, the power supply backup device 16 instantly backs up the power to the RAM 141, so that the control table information of the RAM 141 is stored. It will not be accidentally lost, and the adverse effects on operation will be avoided.

As described above, according to this embodiment,
Complicated commands are organized by volume open processing in the conventional standard label format, etc., and when accessing the descriptors (control table) of volumes and files, except when mounting or unloading, tape motion Since it disappears at all and repositioning does not occur, execution time is greatly shortened,
The operating efficiency of the entire system is improved, and the magnetic tape and head are less likely to deteriorate. Further, since the descriptors for the magnetic tape are collectively managed on the RAM 141 in the magnetic tape storage controller, desired descriptor information can be obtained at any time without a tape operation. For example, it becomes possible to obtain information such as the total number of files required for file search, whether or not it is a multi-reel file, whether or not it is a multi-file reel, and file position information without tape operation, and it is possible to access descriptors. It becomes extremely simple.

Further, at the time of unloading, the control table information is saved from the RAM to the head portion of the magnetic tape for recording data, and the magnetic tape is restored to the RAM when the magnetic tape is mounted. Since backup can be performed without preparing a storage medium and a volatile semiconductor memory having a high access speed can be used for the RAM, the control table can be accessed by the host device at high speed, and the execution time can be further shortened. Further, since the control table information storage area of the RAM is sufficient for one magnetic tape, the load on the memory capacity is small.
Further, when the magnetic tape is automatically positioned at the head position when the magnetic tape is mounted, the descriptor information can be quickly restored without any special search. Further, even if a failure occurs in the power source, the RAM power source is backed up, so descriptor information required for operation on the magnetic tape is not lost, and operational reliability is high.

In the above embodiment, the descriptor information is recorded in the head portion of the magnetic tape. However, the area next to the last file data, the last area of the magnetic tape, and the middle portion of the magnetic tape are recorded. Area, etc., and a plurality of areas among these areas may be combined to have the same descriptor information at a predetermined plurality of locations on the magnetic tape. Further, the RAM stores only the descriptor information for one magnetic tape mounted in the magnetic tape storage device, but a nonvolatile storage medium such as a magnetic disk or an optical disk is used to store descriptor information for a plurality of descriptors. Information may be stored, and in this case, one magnetic tape may be stored as a unit, or a plurality of cohesive units such as a multi-reel file may be stored as a unit. Further, not only the host device accesses the descriptor information, but also when recording the file data on the magnetic tape, the block count, the last block ID, etc. are voluntarily set in the magnetic tape storage control device in the RAM control table. May be additionally stored in.

Also, the restoration of the descriptor information from the magnetic tape to the RAM is not performed at the time of tape mounting, but at any predetermined time after the tape mounting until the time when the descriptor information is required on the upper device side. Well, RAM
The descriptor information can be saved from the disk to the magnetic tape at any time after the access to the descriptor information by the higher-level device or the voluntary access to the descriptor information in the magnetic tape storage controller is finished and before the unloading is completed. It may be performed at a predetermined time point. Although the present invention has been described with reference to the embodiments, modified examples, and application examples, the present invention can be modified in various ways according to the gist of the present invention described in the claims, and the present invention does not exclude these. ..

[0040]

As described above, according to the present invention, the descriptor information instructed to be written by the host device is stored in the descriptor storage means which can be randomly accessed by the descriptor access means, and the descriptor instructed to be read by the host device. Since the information is configured to be read from the descriptor storage means and passed to the host device,
When the host device instructs the magnetic tape storage device to write or read the descriptor information, the magnetic tape storage device writes or reads the descriptor information to or from the randomly accessible descriptor storage means. Since there is no need to perform any special operations on the, the tape motion is completely eliminated, the tape repositioning does not occur, the access to the descriptor information by the host device is simplified, and the execution time of the access related to the descriptor information is reduced. Significantly shorten. In many cases, the descriptors are frequently accessed, but even in such a case, the operating efficiency of the entire system including the host device does not deteriorate.

Further, the descriptor information for the magnetic tape of the multi-reel file includes information indicating that it is a multi-reel file, and the descriptor information for the magnetic tape of the multi-file reel includes information indicating that it is a multi-file reel. By including this information, the host device can always obtain this information without tape motion, and by including the position information on the magnetic tape for each file in the descriptor information for the magnetic tape of the multi-file reel. The positioning of the magnetic tape on the desired file can be performed quickly.

Further, since the descriptor backup means for saving the descriptor information from the descriptor storage means at a predetermined time and restoring the data at another predetermined time is provided, the descriptor storage means can store one magnetic tape. A large number of magnetic tapes can be supported simply by securing an area for storing descriptor information. Further, since the predetermined one or a plurality of areas of the magnetic tape in which the data is stored is used as the backup storage location, it is not necessary to prepare a special storage medium for the backup.

Since the backup storage location is the area of the head portion of the magnetic tape, when the magnetic tape is automatically positioned at the head position when the magnetic tape is mounted, a special search is performed. The descriptor information can be restored quickly without doing so. Also,
When the descriptor storage means is volatile, the control table information is configured to be backed up by the power supply backup device in case of a power failure, so even if a failure such as a power failure, momentary interruption or power failure occurs It is possible to prevent the loss of, and there is no operational failure.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a magnetic tape recording format.

FIG. 4 is a specific configuration diagram of a control table.

FIG. 5 is an explanatory diagram of specifications of extended commands.

FIG. 6 is an explanatory diagram of specifications of extended commands.

FIG. 7 is a flowchart of initialization processing.

FIG. 8 is a flowchart of file control table update processing.

FIG. 9 is a flowchart of an unloading process.

FIG. 10 is a flowchart of a file search process.

FIG. 11 is an explanatory diagram of a standard label type magnetic tape recording format.

FIG. 12 is a specific configuration diagram of a control label in a standard label format.

FIG. 13 is a flowchart of a conventional initialization process.

FIG. 14 is a flowchart of a conventional header label update process.

FIG. 15 is a flowchart of a conventional file search process.

[Explanation of symbols]

 10 magnetic tape storage device 12 magnetic tape drive device 14 magnetic tape storage control device 16 power supply backup device 20 host device 141 RAM 142 MPU

Claims (7)

[Claims] 1. A magnetic tape drive device (12) for recording / reproducing data to / from a magnetic tape managed by a host device (20) by a descriptor, and controlling the magnetic tape drive device according to an instruction from the host device. A magnetic tape storage controller for recording / reproducing data on / from a magnetic tape (1
4) a magnetic tape storage device (10) comprising: descriptor storage means (141) for randomly accessing descriptor information for a magnetic tape in the magnetic tape storage control device; In accordance with the child write command, the descriptor information sent from the host device is written in the descriptor storage means, and in accordance with the descriptor read command from the host device, the desired descriptor information is read from the descriptor storage device and output to the host device. A magnetic tape storage device comprising: 2. The descriptor information for the magnetic tape includes information indicating whether it is a multi-reel file or information indicating whether it is a multi-file reel,
The magnetic tape storage device according to claim 1, wherein: 3. The magnetic tape storage device according to claim 1, wherein the descriptor information for the magnetic tape of the multi-file reel includes position information on the magnetic tape for each file. 4. The descriptor storage means (141) at a predetermined time
Descriptor backup means (142, 1) that saves descriptor information from the
2. The magnetic tape storage device according to claim 1, further comprising: 2). 5. The descriptor backup means uses a predetermined location or a plurality of areas on a magnetic tape for storing data as a storage location for backup. Magnetic tape storage. 6. The magnetic tape storage device according to claim 5, wherein the backup storage location is an area of a head portion of the magnetic tape. 7. The descriptor storage means is a volatile storage means (141), and a power supply backup means (16) for backing up the power supply of the descriptor storage means in the event of a power supply failure is provided. Item 1. A magnetic tape storage device according to item 1.