JP2012181896A - Control method of magnetic tape device, magnetic tape device, and control program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a special component such as a look-ahead head or the like and cyclically store data in a magnetic tape without dividing the data.SOLUTION: When a capacity of a data storage area remaining on a terminal side of a partition as an overwritable area exceeds a preset storage capacity, a logical composition of the partition is retained to continue a writing of new data. However, when the capacity of the data storage area remaining on the terminal side of the partition as the overwritable area does not exceed the preset storage capacity, wraps constituting the partition are cyclically shifted from a partition start end side toward the terminal side in a wrap unit, the logical composition of the partition is updated, and the writing of the new data is continued.

Description

  The present invention relates to a control method, a magnetic tape device, and a control program for the magnetic tape device, in which various data are overwritten and stored in a logical partition constituted by a plurality of wraps included in the magnetic tape.

A general magnetic tape device is designed to write new data one after another with reference to the EOD indicating the final write end position of data on the magnetic tape. Therefore, data can only be recorded sequentially from the beginning to the end of the magnetic tape, and the act of overwriting old data by overwriting old data while leaving new data is not allowed.
In addition to a magnetic tape device that records data sequentially from the beginning to the end of the magnetic tape, multiple wraps consisting of reciprocating tracks are provided on the magnetic tape, and data is stored by setting logical partitions across the wraps. There is a magnetic tape device that manages the area, but even in such a case, data is written continuously from the beginning to the end of the partition while reciprocating the magnetic tape, leaving new data It is the same as the unidirectional magnetic tape device described above in that it is not allowed to overwrite old data and overwrite new data.
The reason why overwriting is not allowed is that if new data is overwritten on a storage area where data has already been written, the consistency of the data from where continuous data is written to the subsequent storage area This is because there is a disadvantage that it is impossible to determine whether the data is taken.
Therefore, even if these magnetic tape devices are used to overwrite new data, all data following the new data overwriting end position is treated as invalid data, that is, unreadable data. For example, when recording multiple generations of data as a backup, even if the total capacity of data for the number of generations to be stored is a capacity that can be contained in a single magnetic tape, It becomes necessary to use it, and the operational efficiency of the magnetic tape is deteriorated.

As a technique for improving such an inconvenience, as disclosed in Patent Document 1, a pre-read head as a new component is added in the magnetic tape device, and the MAP information recorded on the magnetic tape is added. A method has been proposed in which data is cyclically recorded in a specific area on a magnetic tape by reading with a read-ahead head and referring to determination data on whether or not it can be used cyclically, which is included in MAP information.
However, this method requires a special component, a look-ahead head. In addition, when data is divided and stored on the start side and the end side of the magnetic tape, it is necessary to re-position the magnetic head during the data reading operation, and the start end read separately. Since special processing such as combining the data on the side and the end side is also required, there is a disadvantage that the software of the host device must be changed. In addition, it is necessary to determine where the data written in the storage area following the written data is consistent data, and complicated processing such as recording a dummy file header is required. There is a problem that it is difficult to realize in terms of specifications.

Previously, the storage format of data on magnetic tape was generally different for each OS and software. However, in recent years, data storage on magnetic tape has become independent of OS and software. A recording format capable of writing and reading, for example, LTFS (Linear Tape File System) has been proposed.
This uses the partitioning function supported by LTO-5 to divide the storage area of the magnetic tape into a content area and an index area, and store various data and other data bodies in the content area while indexing In the area, index information for making it possible to handle the data body in the content area, for example, information such as the data name and data size required for reading the data body and the reading start position thereof is stored, and write-once type It is an attempt to improve the utilization efficiency of the magnetic tape which is the storage medium of the above.
This recording format is directly related to the problem of generation backup, that is, the deterioration of the operation efficiency of magnetic tape caused by the inability to overwrite data, the problem of positioning processing due to data division, and the complication of data combining processing Not what you want. However, because the specifications are different from the previous general recording format using magnetic tape, in the situation where data is managed with the help of LTFS specifications, old data remains on the old data while keeping the new data on the magnetic tape. Of course, if you try to use the new data by overwriting it, you will need to access the data itself using the index information on the magnetic tape. Be careful when handling

  In addition, about the handling of the magnetic head which moves between wraps on a magnetic tape, the setting of the partition which straddles a wrap, etc., as seen in, for example, Patent Document 2 and Patent Document 3, it is already common. .

JP-A-6-139650 (paragraph 0003, paragraph 0007, paragraph 0011, FIG. 1) JP-T-2005-516340 (paragraph 0013, paragraph 0020, FIG. 5) JP 2005-63444 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling a magnetic tape apparatus and a magnetic tape which can store data cyclically on a magnetic tape without requiring a special component such as a read-ahead head and without dividing the data. To provide an apparatus and its control program.

The method for controlling a magnetic tape device according to the present invention is a method for controlling a magnetic tape device in which data is overwritten and stored in a logical partition formed by a plurality of wraps of the magnetic tape, and the object is achieved. To do
Determining whether or not the capacity of the data storage area remaining as an overwritable area on the end side of the partition when writing data to the partition exceeds a preset storage capacity;
If the capacity of the data storage area remaining as an overwritable area at the end of the partition exceeds the preset storage capacity, while maintaining the logical configuration of the partition and continuing to write new data,
If the capacity of the data storage area remaining as the overwritable area on the end side of the partition does not exceed the preset storage capacity, the wraps constituting the partition are cyclically shifted from the partition start side to the end side in units of laps. In addition, after the logical configuration of the partition is updated, writing of new data is continued.

In particular, the present invention relates to a control method for a magnetic tape device in which index information including a data main body and a read start position of the data main body is overwritten in a logical partition constituted by a plurality of wraps included in the magnetic tape and stored cyclically. In order to achieve the same purpose as described above,
Determining whether it is necessary to expand the data storage area remaining as an overwritable area on the end side of the partition when writing the data body and index information to the partition;
If it is not necessary to expand the data storage area, while maintaining the logical configuration of the partition and continuing to write new data body and index information,
If it is necessary to expand the data storage area, the index information corresponding to the data body stored in the starting wrap constituting the partition is deleted, and the block ID of the first data block of the next wrap is valid. The data is stored together with undeleted index information as an ID, and the wraps constituting the partition are cyclically shifted from the start side to the end side of the partition in units of laps, and the logical structure of the partition is updated and a new data body and index are updated. A configuration characterized by continuing to write information is applied.

The magnetic tape device according to the present invention is a magnetic tape device that overwrites data in a logical partition constituted by a plurality of wraps included in the magnetic tape and cyclically stores the data, and in order to achieve the above object,
Remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition when writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as the overwritable area exceeds the preset storage capacity, the logical configuration of the partition is maintained while the remaining storage area is maintained. When it is determined by the area determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is circulated in units of laps on the partition start side. And a partition restructuring means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge;
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. If the value is less than the block ID value, the non-volatile memory has positioning control means for positioning the magnetic head in the partition in which the wrap number is stored as the start of the partition.

In particular, in a magnetic tape device that overwrites and stores index information including a data body and a reading start position of the data body in a logical partition constituted by a plurality of wraps that the magnetic tape has. ,
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side, and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Each time, the index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched,
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While the apparatus permits, the validity of the block ID value of the index information detected by the index information validity determination means stored together with the latest index information without the match / mismatch determination means determining a match. If it is determined that the block ID is less than Applying a configuration in which characterized in that an output information limiting means for informing the read error of the index information to the host device to read the broadcast as a non-executable.

The control program for a magnetic tape device according to the present invention includes a microprocessor included in a magnetic tape device that overwrites data in a logical partition constituted by a plurality of wraps of the magnetic tape and stores the data cyclically.
A remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition at the time of writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as an overwritable area exceeds a preset storage capacity, the logical structure of the partition is maintained, while the remaining storage area When it is determined by the determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is cyclically terminated from the partition start end side in units of laps. Partition rebuilding means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge; and
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. When the value is less than the block ID value, the non-volatile memory functions as positioning control means for positioning the magnetic head in the partition in which the wrap number is stored as the start of the partition.

In particular, in a control program for a magnetic tape apparatus that overwrites and stores index information including a data main body and a reading start position of the data main body in a logical partition constituted by a plurality of wraps included in the magnetic tape. In that case, the microprocessor included in the magnetic tape device is
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information each time,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched, and
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While permitting the apparatus, the block ID value of the index information detected by the index information validity determining unit is stored together with the latest index information without the matching / non-matching determining unit determining a match. If it is determined that the value is less than the valid block ID value, the index Applying a configuration in which characterized in that to function reading error of the index information as output information limiting means for notifying the host device to read the information as non-executable.

  The magnetic tape device control method, magnetic tape device, and control program therefor according to the present invention provide a logical configuration of a partition if the capacity of a data storage area remaining as an overwritable area at the end of the partition exceeds a preset storage capacity. If the capacity of the data storage area that remains as an overwritable area on the end side of the partition does not exceed the preset storage capacity, the wrap that constitutes the partition is a lap unit. Since the partition is shifted from the partition start side to the end side and the logical configuration of the partition is updated to continue writing new data, the data that remains as an overwritable area at the end of the logical partition While increasing the storage area sequentially, the data is divided. Without, it can be stored cyclically data on a magnetic tape.

  In particular, in a magnetic tape device control method, a magnetic tape device, and a control program for overwriting a data main body and index information in a logical partition constituted by a plurality of wraps included in a magnetic tape and storing them cyclically If it is not necessary to expand the data storage area that remains as an overwritable area at the end of the partition, the partition logical structure is maintained and writing of new data body and index information is continued, while the data storage area is expanded. If necessary, the wraps that make up the partition are cyclically shifted from the start side of the partition to the end side in units of wraps, and the writing of new data and index information is continued after updating the logical configuration of the partition. Because of the logical partition The data storage area that remains as an overwritable area on the end side can be cyclically stored on the magnetic tape without being divided, and the logical structure of the partition can be updated at the beginning of the previous partition. The index information corresponding to the data body stored in the wrap is deleted, and the undeleted index with the block ID of the first data block stored in the next wrap, that is, the first wrap of the updated partition as the effective block ID Since it is stored together with information, when accessing the data body using the index information of the magnetic tape, malfunction that tries to move the magnetic head to the invalid data storage area or the wrong data storage area Can be prevented in advance.

It is the block diagram which simplified and showed the structure of the magnetic tape apparatus of one Embodiment to which this invention was applied, the cartridge which accommodated the magnetic tape which a magnetic tape apparatus uses, and the high-order apparatus using a magnetic tape apparatus. First and second embodiments). It is the conceptual diagram which simplified and showed about the arrangement | sequence of the information memorize | stored in the non-volatile memory fixed to the cartridge of the magnetic tape of the embodiment (1st Embodiment). 3 is a flowchart showing an outline of data writing processing in the magnetic tape device of the embodiment (first embodiment). 3 is a flowchart illustrating an outline of data reading processing in the magnetic tape device of the embodiment (first embodiment). 3 is a flowchart showing an outline of a magnetic head positioning process in the magnetic tape device of the embodiment (first embodiment). It is the conceptual diagram which simplified and showed the basic writing format of the data to the magnetic tape on the assumption of LTFS (general example). It is the conceptual diagram which simplified and showed concrete writing of the data to the magnetic tape on the assumption of LTFS (general example). It is the conceptual diagram which simplified and showed specific writing of the data on the magnetic tape on the assumption of LTFS including additional data (general example). It is the conceptual diagram which simplified and showed about the arrangement | sequence of the information memorize | stored in the non-volatile memory fixed to the cartridge of the magnetic tape apparatus of one Embodiment to which this invention is applied (2nd Embodiment). It is the flowchart shown about the outline of the partition reconstruction process in the magnetic tape apparatus of the embodiment (2nd Embodiment). It is the flowchart shown about the outline of the index information reading process in the magnetic tape apparatus of the same embodiment (2nd Embodiment). It is the figure which simplified and showed about the structural example of the magnetic tape provided with the several wrap (general example).

  Next, some embodiments for carrying out the present invention will be specifically described with reference to the drawings.

[First Embodiment]

  FIG. 1 is a simplified diagram of the configuration of a magnetic tape device 1 according to an embodiment to which the present invention is applied, a cartridge 3 containing a magnetic tape 2 used by the magnetic tape device 1, and a host device 4 using the magnetic tape device 1. FIG.

  The host device 4 issues a read / write command to the magnetic tape device 1, and the magnetic tape device 1 that receives the read / write command reads / writes data from / to the magnetic tape 2 as before.

  The magnetic tape device 1 moves the magnetic head 5 used for reading / writing and erasing data, a magnetic tape feeding mechanism (not shown), and the magnetic head 5 along the width direction of the magnetic tape 2, that is, the wrap arrangement direction. A known element such as a seek mechanism is provided. In some cases, the magnetic head 5 may be configured by combining a magnetic head for erasure, a magnetic head for writing, and a magnetic head for reading. However, various configurations of the magnetic head 5 are already known. I will not explain it.

  The microprocessor 6 of the magnetic tape apparatus 1 that drives and controls the magnetic head 5, the magnetic tape feeding mechanism, the seek mechanism and the like in response to various commands from the host apparatus 4 includes the microprocessor 6 as a remaining storage area determination means, partition A non-volatile memory 7 storing a magnetic tape device control program (see FIGS. 3 to 5) and various parameters for functioning as reconstruction means, partition information updating means and positioning control means is connected.

  Further, the nonvolatile memory 7 includes a storage capacity setting value used as a threshold when the remaining storage area determination unit determines whether or not the logical configuration of the partition needs to be updated, and a partition reconstruction unit includes a partition The setting value of the partition shift amount of the lap unit used when shifting can be freely set as a kind of parameter.

In this embodiment, an interface 9 for transferring data to and from a non-volatile memory 8 (hereinafter referred to as a cartridge memory 8) fixed to the cartridge 3 is further provided in the magnetic tape device 1 and magnetically. Data is exchanged between the microprocessor 6 of the tape device 1 and the cartridge memory 8 of the magnetic tape 2 mounted on the magnetic tape device 1.
The interface 9 may be a mechanical contact for realizing electrical connection, or may be a non-contact type using short-range wireless communication or the like.

  As shown in FIG. 2, the cartridge memory 8 stores at least the wrap number of the physical wrap that is the beginning of the partition (beginning of partition / hereinafter referred to as BOP) updated by the partition restructuring means. A BOP position information storage area 311; an EOP position information storage area 312 for storing the wrap number of the physical wrap that is the end of the partition updated by the partition reconstruction means (End of Partition / hereinafter referred to as EOP); BOP Block that stores the block ID of the first data block of the wrap that is the start of the partition updated by the partition restructuring means, that is, the logical position of the first data block recognized by the host device 4 with reference to the start of the partition The ID storage area 313 and the host device 4 are based on the beginning of the partition. As a standard, an EOD Block ID storage area 314 for storing a logical block ID of a data block recognized as a final data write end position at that time is provided.

  The BOP position and EOP position mentioned here are not the physical start and end of the area divided on the magnetic tape 2, but which wrap in the area has the start and end of the logical partition. It is information to show.

  FIG. 12 shows a simplified configuration example of the magnetic tape 2 having a plurality of wraps. In this example, one track is formed by setting a track in the forward direction and a track in the return direction, and various data are logically transferred from the beginning of a logical partition (for example, wrap 0) while reciprocating the magnetic tape 2. Is written continuously toward the end of a typical partition (eg, wrap 9).

  Next, referring to the flowcharts of FIGS. 3 to 5, the magnetic tape device control method and magnetic tape device control program in this embodiment, the remaining storage area determination means, and the partition in the magnetic tape device 1 in this embodiment The processing operation of the microprocessor 6 functioning as a reconstruction unit, a partition information update unit, and a positioning control unit will be specifically described.

  First, the data writing process will be described with reference to FIG.

When writing data to the partition, when the magnetic tape device 1 receives a Write command from the host device 4 (step S101), first, the microprocessor 6 functioning as the remaining storage area determination means has a storage capacity used as a threshold value. The setting value is read from the nonvolatile memory 7, and the setting value is compared with the capacity of the data storage area that remains as the overwritable area at the end of the partition at present, and the data storage area that remains as the overwritable area at the end of the partition It is determined whether or not a preset storage capacity value is exceeded (step S102).
The capacity of the data storage area remaining as an overwritable area at the end of the partition at present is, for example, the wrap arrangement position (wrap number) where the magnetic head 5 is located, the traveling direction of the magnetic tape 2, and the take-up reel of the magnetic tape 2. It can be easily obtained by multiplying the remaining magnetic tape length obtained from the number of rotations by the storage capacity per unit length of the magnetic tape 2. Of course, the tape length may be used as a setting value instead of the storage capacity used as the threshold value, and the remaining magnetic tape length may be directly compared with the setting value.

  If the result of the determination in step S102 is true and it is clear that the capacity of the data storage area remaining as an overwritable area exceeds the preset storage capacity, it is necessary to increase the data storage area of the partition Therefore, the microprocessor 6 functioning as the partition restructuring means maintains the logical configuration of the partition as it is, and stores the EOD Block ID storage area 314 of the cartridge memory 8 in accordance with the Write command from the host device 4 as in the prior art. Data is written following the previously stored data write end position, and the current data write end position is updated and stored in the EOD Block ID storage area 314 of the cartridge memory 8 (step S104).

  On the other hand, if the determination result in step S102 is false and it is clear that the capacity of the data storage area remaining as an overwritable area does not exceed the preset storage capacity, the data storage area of the partition is increased. It means you need to.

In this case, the microprocessor 6 functioning as the partition restructuring unit updates the logical configuration of the partition by cyclically shifting the wraps constituting the partition from the partition start side to the end side in units of laps, and functions as the partition information update unit. The microprocessor 6 to be updated updates and stores the wrap number of the wrap at the beginning of the partition updated by the partition restructuring means in the BOP position information storage area 311 of the cartridge memory 8 and updates it by the partition restructuring means. The wrap number of the wrap at the end of the partitioned partition is updated and stored in the EOP position information storage area 312 of the cartridge memory 8, and the wrap number at the start of the partition updated by the partition reconstruction means is further stored. The block ID of the data block is updated and stored in the BOP Block ID storage area 313 of the cartridge memory 8 (step S103). Data is written subsequent to the previous data write end position stored in the Block ID storage area 314, and the current data write end position is updated and stored in the EOD Block ID storage area 314 of the cartridge memory 8 (step). S104).
For example, the lap number 0 is stored in the BOP position information storage area 311 of the cartridge memory 8 and the lap number 9 is stored in the EOP position information storage area 312 at the time of step S 101 when the write command is received from the host apparatus 4. In a situation where a partition having a wrap number 0 as a starting point and a wrap number 9 as a ending partition is used, the block ID of the first data block of the wrap number 1 wrap is 100, and a non-volatile memory 7 is set to 1 as the setting value of the partition shift amount in units of laps, and it is assumed that the total physical number of wraps on the magnetic tape 2 is 9, and the determination result in step S102 under this situation is as follows. If it becomes false and it becomes necessary to increase the data storage area of the partition, the process in step S103 The BOP position information storage area 311 of the cartridge memory 8 is updated and stored with a lap number 1 (0 + 1 = 0 [1 is the set value of the shift amount]), and the lap number 0 is stored in the EOP position information storage area 312 of the cartridge memory 8. (9 + 1 = 10, but the total number of wraps is 9 and the partition is cyclically shifted, so the value corresponding to 10 is 0) is updated and stored, and the BOP Block ID of the cartridge memory 8 In the storage area 313, the block ID value 100 is updated and stored.

  Block ID even if the data is stored in the wrap with wrap number 0 that was used to configure the beginning of the partition and the data on the wrap with wrap number 1 that is used to configure the start of the partition. Data whose value is less than 100, that is, all data whose contents continue from the wrap of wrap number 0, become invalid data when the processing of step S103 related to partition reconstruction is executed. Since the block ID value 100 of the first data block of the wrap with the wrap number 1 newly set as the start of the partition is stored in the BOP Block ID storage area 313 of 8, the execution of the positioning process of the magnetic head 5 is blocked. By limiting the ID value to a range that is 100 or more, invalidated data storage areas and incorrect data storage areas Malfunction tending to move the magnetic head 5 can be prevented in.

  Through the above processing, the data storage area remaining as an overwritable area on the end side of the logical partition can be cyclically stored on the magnetic tape 2 without being divided while sequentially increasing the data storage area.

  As a result, the latest data is always written in the vicinity of the end of the partition, and is reliably held for a long time.

  Next, the data reading process will be described with reference to FIG.

When the magnetic tape device 1 receives the Read command from the host device 4, the microprocessor 6 drives and controls the magnetic head 5 to start reading data from the magnetic tape 2 (step S201). It is determined whether or not the end of the lap has been reached (step S202).
The determination as to whether or not the magnetic head 5 has reached the end of any lap is made, for example, by the wrap arrangement position (lap number) where the magnetic head 5 is located, the traveling direction of the magnetic tape 2, and the winding of the magnetic tape 2. It can be easily obtained from the number of rotations of the take-up reel.

  If the determination result in step S202 is false and it is clear that the magnetic head 5 is not at the end of the lap, the microprocessor 6 continues to read the data as it is and sends the read data to the host device 4. Transfer (step S207).

  On the other hand, if the determination result in step S202 is true and it is clear that the magnetic head 5 has reached the end of any lap, the microprocessor 6 further determines that the magnetic head 5 is currently By comparing the lap number of the tracked lap with the lap number of the terminal lap stored in the EOP position information storage area 312 of the cartridge memory 8, the lap currently being tracked by the magnetic head 5 is determined as the partition lap number. It is determined whether or not it is a logical end wrap (step S203).

If the determination result in step S203 is true and it is clear that the wrap currently tracked by the magnetic head 5 is the logical end wrap of the partition, the microprocessor 6 An EOP signal indicating that 5 has reached the end of the logical end wrap of the partition is transmitted to the host device 4, and the data reading process is terminated as it is.
Therefore, there is no fear that invalidated data or unguaranteed data is read from the magnetic tape 2 beyond the logical end wrap of the partition.

  If the determination result in step S203 is false and it is clear that the lap currently being tracked by the magnetic head 5 is not the logical end wrap of the partition, the microprocessor 6 further Then, it is determined whether or not the wrap currently tracked by the magnetic head 5 is the physical end wrap of the partition (step S204).

If the determination result in step S204 is true and it is clear that the wrap currently tracked by the magnetic head 5 is the physical end wrap of the partition, the microprocessor 6 After the mechanism is driven to move the magnetic head 5 to the physical start wrap of the partition (step S205), data reading is continued in the same manner as described above, and the read data is transferred to the host device 4. (Step S207).
In this case, since the partition wrap structure itself is logically continuous, the data reading process can be continued.
Considering the movement of the magnetic head 5 from the physical end wrap to the physical start wrap, the number of wraps on the magnetic tape 2 is an odd number, and the movement in the seek direction (without the rewinding operation of the magnetic tape 2 ( It is preferable that the magnetic head 5 can be moved from the physical end wrap to the physical start wrap in a short time only by moving the wrap in the arrangement direction.

  If the determination result in step S204 is false and it is clear that the wrap currently tracked by the magnetic head 5 is not the physical end wrap of the partition, the microprocessor 6 To move the magnetic head 5 to the beginning of the next lap as in the prior art (step S206), continue reading data and transfer the read data to the host device 4 (step S206). S207).

  With the above processing, it is possible to appropriately read data written on the magnetic tape 2 cyclically.

  Next, the positioning process of the magnetic head 5 will be described with reference to FIG.

  When the magnetic tape device 1 receives a positioning command such as Space, Locate or Rewind from the host device 4, the microprocessor 6 functioning as a positioning control unit first stores it in the BOP position information storage area 311 of the cartridge memory 8. The wrap number of the wrap that constitutes the start end of the partition being stored, the block ID of the first data block of the wrap that is the start end of the partition stored in the BOP Block ID storage area 313, and the EOD Block ID storage area 314 The block ID of the final data write end position with reference to the start end of the stored partition is read and temporarily stored (step S301).

  Next, the microprocessor 6 functioning as a positioning control means sets the block ID value of the positioning target given from the host apparatus 4 together with the positioning command to the block ID of the first data block stored in the BOP Block ID storage area 313. Whether or not the block ID value of the positioning target is equal to or smaller than the block ID value of the final data writing end position stored in the EOD Block ID storage area 314, that is, the positioning command At the same time, it is determined whether or not the value of the positioning target block ID given from the host device 4 is within the range of the storage area storing the valid data (step S302).

  Here, when the determination result in step S302 is true and it is clear that the value of the positioning target block ID is within the range of the storage area storing the valid data, it functions as positioning control means. The microprocessor 6 uses a magnetic tape feeding mechanism (not shown) according to the positioning target block ID value given from the host device 4 with reference to the starting end of the wrap constituting the starting end of the partition stored in the BOP position information storage area 311 And the drive of the seek mechanism to position the magnetic head 5 at the designated position (step S303).

  If the determination result in step S302 is false and it is clear that the value of the positioning target block ID is not within the range of the storage area storing the valid data, the micro that functions as positioning control means. The processor 6 further determines whether or not the value of the target block ID specified by the positioning command is less than the block ID value of the first data block stored in the BOP Block ID storage area 313, that is, positioning. Is the portion corresponding to the storage area of the past data invalidated immediately after the start of the partition currently used (step S304). Ignore the positioning target block ID given from the device 4, and drive and control the magnetic tape feeding mechanism and seek mechanism (not shown) The magnetic head 5 is positioned at the start end of the wrap that forms the start end of the partition stored in the information storage area 311, and a signal indicating that the magnetic head 5 is positioned at the start end of the currently used partition is transmitted to the host device. (Step S305).

  Also, it is clear that the determination result in step S304 is false and the value of the positioning target block ID exceeds the block ID value of the final data writing end position stored in the EOD Block ID storage area 314. In this case, the microprocessor 6 functioning as a positioning control means ignores the positioning target block ID value given from the host device 4 and drives and controls a magnetic tape feeding mechanism and a seek mechanism (not shown). The magnetic head 5 is positioned at the final data write end position stored in the EOD Block ID storage area 314, and a signal indicating that the magnetic head 5 is positioned at the final data write end position is transmitted to the host device. (Step S306).

  Therefore, even if the positioning to the invalid block ID is designated by the positioning command from the host device 4, the current position of the magnetic head 5 is not lost, and the invalid data storage is performed. A malfunction that attempts to move the magnetic head 5 to an area or an erroneous data storage area can also be prevented.

Further, when it becomes necessary to confirm the current position of the magnetic head 5 by the Read Position command from the host device 4, or when there is a positioning request specifying a block ID such as the Locate command, that is, effective data storage. When it is necessary to handle a block ID that exceeds the area, the BOP Block read from the BOP Block ID storage area 313 of the cartridge memory 8 is added to the accumulated block number (accumulated data block number + accumulated file mark number) from the BOP. The magnetic head 5 is positioned at the position where the ID value is added.
With this process, even after invalidating the data on the wrap that constitutes the beginning of the partition and cyclically connecting it to the end of the partition, the block where the data is written can be accessed using the same block ID as before. For example, it is possible to some extent to read past data that is logically invalidated by rebuilding the partition but whose data content is significant.

The setting value of the storage capacity used as a threshold when the remaining storage area determination means determines whether or not the logical configuration of the partition needs to be updated is appropriately stored in the nonvolatile memory 7 according to the capacity of the data to be handled. Can be updated and set. Naturally, when the data written in one writing process has a large capacity, the setting value of the storage capacity used as the threshold is set to a large value, and the data written in one writing process has a small capacity In this case, the setting value of the storage capacity used as the threshold value is also set to a small value.
Therefore, the determination process in step S102 for determining whether or not the data storage area remaining as the overwritable area on the end side of the partition exceeds the preset value of the storage capacity is substantially the present It may be said that this is a determination process for determining whether or not the data requested to be written can be written to the current partition without being divided.

Here, as an example, a case has been described in which the wraps constituting the partition are shifted one lap at a time when the partition is reconstructed, but it is also possible to cyclically shift the wraps constituting the partition several laps.
The wrap shift amount can be appropriately updated and set in the nonvolatile memory 7 in accordance with the capacity of data to be handled, as in the case of the storage capacity setting value described above.

[Second Embodiment]

  Next, a description will be given of an embodiment in which index information including a data body and a read start position of the data body is overwritten in a logical partition constituted by a plurality of wraps included in the magnetic tape 2 and stored cyclically. To do.

  Index information for dividing the storage area of the magnetic tape 2 into a content area and an index area, and storing the data body including various files in the content area, while allowing the data body in the content area to be handled, For example, a write-once storage system that stores information such as the data name, data size, and read start position required for data reading in the index area is already known as, for example, LTFS (Linear Tape File System). is there.

  Here, a basic data writing format on the magnetic tape 2 on the premise of LTFS will be briefly described with reference to FIG. 6 and FIG.

As shown in FIG. 6, the data written to the magnetic tape 2 in this format is the contents of the data recorded as a file in the host device 4, for example, the content area on the magnetic tape 2 with FileA, FileB, and FileC as the data body. The index information is written in the index area 72 so that the data body in the contents area 71 such as FileA, FileB, and FileC can be handled.
As index information, the data name 721 (consent with the file name) required for reading the data body, for example, FileA, FileB, and FileC, the size 724 (consent with the data length) of each data body, and the reading of each data body A block ID 722 of the data block to be a position and a start offset 723 indicating from which byte in the data block the content of each data body is recorded are written.
Actually, the index information includes, in addition to these data, the date and time of creation of the data body, the date and time of update, and the attributes of the data body (such as read-only). The description in each figure is omitted because there is no relevant relationship.

Here, assuming that two data bodies such as FileD and FileE are newly written in addition to the three data bodies written as shown in FIG. 6 such as FileA, FileB, and FileC, FIG. 7 shows. As described above, the contents of the content area 71 and the contents of the index area 72 written before, that is, all the information located on the left side of BlockID = N in FIG. Also, FileD and FileE are written as data bodies in the new content area 71 generated on the right side, and the data name 721 of each data body is written in the new index area 72 subsequent to the new content area 71 in the same manner as described above. And the block ID 722 and start offset 723 of the data block that is the read start position, and the data body size 724 It becomes written to it.
As can be seen from the comparison between FIG. 6 and FIG. 7, not only FileD and FileE but also the previous index area 72 generated on the right side of BlockID = N corresponding to the writing of FileD and FileE was written before. Index information of FileA, FileB, and FileC is carried over as it is.
When the data body recorded on the magnetic tape 2 is deleted, the magnetic storage of the data body itself stored in the content area 71 is not deleted, but the latest index area 72 is simply deleted. That is, in the example of FIG. 7, the index information corresponding to the data body to be deleted is deleted on the index area 72 located on the right side of BlockID = N, and the contents of the index area 72 from which the index information has been deleted are updated. Thus, it is assumed that the deletion of the data body has been completed.

  As described above, since the latest index area 72 includes all of the information necessary for accessing the previously written data body, the upper level apparatus 4 stores only the latest index area 72. It is possible to access all valid data bodies stored on the magnetic tape 2.

  Note that the index information may be written to a plurality of partitions. Here, as an example, a case where data reading / writing, partition reconstruction, and reading of index information are performed on the magnetic tape 2 having one partition will be described, but the same applies to the magnetic tape 2 having a plurality of partitions. It is possible to apply this processing operation.

  Even when managing the magnetic tape 2 on the premise of LTFS, the hardware configuration itself of the magnetic tape device 1 is not different from the normal one, so the configuration of the magnetic tape device 1 is the same as in the first embodiment. The description and FIG. 1 are incorporated, and detailed description is omitted here.

However, in this embodiment, the microprocessor 6 of the magnetic tape device 1 includes command determining means for determining whether or not a data storage area expansion command is input from the host device 4;
If the command determination means does not detect the input of the data storage area extension command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area extension command, the wrapping of the starting edge constituting the partition is performed. Deletes the index information corresponding to the data body stored in the latest index area and stores the block ID of the first data block of the next wrap as a valid block ID in the latest index area together with the undeleted index information. Partition reconfiguration means for cyclically shifting the wrap constituting the partition from the start side of the partition to the end side in units of laps and updating the logical configuration of the partition,
When a read command for index information of one generation or more before is given from the host device 4, the block ID value of the index information is detected retroactively from the previous generation in order, and the block ID of the index information is Index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information each time it is detected,
When it is determined that the block ID of the index information detected by the index information validity determination unit is greater than or equal to the value of the valid block ID stored together with the latest index information, the index information is received from the host device 4. A coincidence / non-coincidence judging means for judging whether or not the index information given by the read command of
When the coincidence / non-coincidence judging unit judges coincidence, internal reading of this index information is executed, and the valid block ID value stored together with the latest index information is read in the matching index information. The host device compares the size with each of the start positions and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. 4 is a valid block in which the block ID value of the index information detected by the index information validity determining unit is stored together with the latest index information without the matching / non-matching determining unit determining a match. Reading index information when it is determined that the value is less than the ID value Teeth reading error of the index information will function as output information limiting means for notifying the host device 4 as a non-run the.

  A magnetic tape device control program (see FIGS. 10 to 11) for causing the microprocessor 6 to function as command determination means, partition reconstruction means, index information validity determination means, coincidence mismatch determination means, and output information restriction means is nonvolatile. Stored in the memory 7.

  In the cartridge memory 8 of this embodiment, the BOP position information storage area 311, the EOP position information storage area 312, the BOP Block ID storage area 313, and the EOD Block ID storage area 314 already described in the first embodiment are used. In addition, as shown in FIG. 9, various information relating to each lap on the magnetic tape 2, that is, a lap number storage area 315 for storing the lap number of each lap, and a data block serving as the starting end of each lap A start block ID storage area 316 for storing the block ID, a data block number storage area 317 for storing the number of data blocks in each lap, and a file for storing the number of file marks (indexes) set in each lap A mark number storage area 318 is provided.

  Next, referring to the flowcharts of FIGS. 10 to 11, the magnetic tape device control method and magnetic tape device control program in this embodiment, the command determination means in the magnetic tape device 1 of this embodiment, and the partition reconstruction The processing operation of the microprocessor 6 functioning as means, index information validity determination means, match / mismatch determination means, and output information restriction means will be described in detail.

  First, referring to FIG. 10, a process for reconstructing a partition will be described.

In this embodiment, unlike the case of the first embodiment described above, the process of rebuilding a partition is executed only when a data storage area expansion command is explicitly input from the host device 4. Therefore, the remaining storage area determination means as in the first embodiment described above is not required.
The timing at which the host device 4 outputs the data storage area expansion command to the magnetic tape device 1 is determined, for example, when the wrap tracked by the magnetic head 5 approaches the logical end wrap of the partition while data is being written. The upper level device 4 acquires the storage capacity remaining in the partition of the magnetic tape 2 via the magnetic tape device 1, based on the early warning signal output from the magnetic tape device 1 to the higher level device 4. For example, it may be executed when the remaining capacity falls below a certain level. Of course, it is also possible to perform the process of rebuilding the partition regardless of the storage capacity remaining in the partition of the magnetic tape 2, and the incidental conditions for rebuilding the partition are not necessarily required.

  Further, since the basic data writing format on the magnetic tape 2 conforms to the LTFS format, processing related to reading of the data body from the content area 71 on the magnetic tape 2 and positioning of the magnetic head 5 is performed. In the case of execution, as a pre-processing for that purpose, the host device 4 needs to acquire the index information stored in the index area 72 on the magnetic tape 2, and when moving the wrap to reconstruct the partition However, there is a difference from the first embodiment described above in that care must be taken in handling the index information.

  When the magnetic tape device 1 receives a data storage area expansion command from the host device 4, the microprocessor 6 functioning as a command determination unit detects this, and first, a magnetic tape feeding mechanism and a seek mechanism (not shown) and the magnetic head 5 are not shown. Is controlled to read the latest index information from the latest index area 72 on the magnetic tape 2 and temporarily store it, and from the BOP position information storage area 311 of the cartridge memory 8, the beginning of the partition currently used The number of data blocks stored in the start block ID storage area 316 and the number of data blocks stored in the data block number storage area 317 corresponding to the same lap number as the lap number is read Is read (step S401).

Then, the microprocessor 6 functioning as the partition reconstructing means sends the information, that is, the data name 721 included in the index information of the latest index area 72, the block ID 722 and the start offset 723 corresponding to the data name 721. Information acquired from the latest index area 72 on the tape 2), and a block ID 316 and data block number 317 (information acquired from the cartridge memory 8) as information related to the wrap constituting the start of the partition at the present time. ), The data body of which the data name 721 is stored using the latest index area 72 on the magnetic tape 2 is stored on the wrap constituting the beginning of the partition. On the wrap that makes up the starting edge The data name 721 of the stored data body and all related information, that is, the block ID 722 and start offset 723 of the data block that is the read start position, and data of the data body size 724 are currently stored in the microprocessor. 6 deletes all the index information temporarily stored in the index information 6 and stores the index information temporarily stored in the microprocessor 6 without deleting the index information newly generated on the magnetic tape 2 as shown in FIG. The area 72 is rewritten in the form of additional writing, and the new index area 72 is a wrap that is to be newly set as the start of the partition by reconstructing the partition, that is, the wrap that currently forms the start of the partition. One lap number value cyclically than the lap number of The value of the block ID of the first data block of the lap Kinatsugi, is stored as the value of the valid BlockID725. At this time, the value of the block ID at the storage start position of the index information one generation before on the magnetic tape 2 is also stored in the new index area 72 (step S402).
Further, the value of the effective block ID 725 is updated and stored in the BOP Block ID storage area 313 of the cartridge memory 8 as in the case of the first embodiment described above.

  Here, the details of the new index information added in the process of step S402 will be briefly described with reference to FIGS.

As shown in FIG. 7, assuming that blocks with a block ID up to M + 1 are included on the wrap that constitutes the beginning of the partition at the time before the rebuilding of the partition, FileA and FileB are at the beginning. It is recorded on the wrap, that is, the wrap whose data is invalidated by rebuilding the partition. Therefore, in this case, as shown in FIG. 8, the data name 721 of FileA and various information related thereto, that is, the block ID 722 and the starting offset 723 that are positioned side by side with FileA and the size 724 of the data body. Is deleted from the index information in the temporary storage, and similarly, the data name 721 of FileB, various information related thereto, that is, the block ID 722 and the starting offset 723 that are positioned side by side with FileB, and the size 724 of the data body It is deleted from the index information in the temporary storage.
In addition, since the wrap next to the wrap whose data is invalidated starts from the block whose block ID is M + 2, the effective value of the block ID 725 is M + 2. Therefore, the value of M + 2 as a valid Block ID 725 value is stored in the new index area 72 together with the remaining index information without being deleted.
Note that the latest index information in the description of step S401, that is, index information to be read is index information stored in the index area 72 shown at the right end in FIG. 7, and the CPU 6 performs processing in step S402. 8 is the index area 72 described at the right end in FIG. 8 as the write destination of the index information temporarily stored and the effective Block ID 725 value. As already described, since it is a write-once type storage format, the contents of the index information to be read in the process of step S401 are the index area 72 shown at the right end in FIG. 7, that is, 2 from the right in FIG. The index information 72 that remains in the index area 72 located in the second position and remains in the undeleted state even after receiving the process of step S402, and the value of the effective BlockID 725 obtained in the process of step S402 are: It is stored in the index area 72 described at the right end in FIG.
Further, the index information of the previous generation at this point is the index information of the index area 72 described at the right end in FIG. 7, that is, the index area 72 located second from the right in FIG. The index information storage start position of the index area 72 located second from the right is the index of the previous generation in the new index area 72 described at the right end in FIG. It is stored as the block ID of the information storage start position.

The processing in step S403 for updating the logical configuration of the partition by cyclically shifting the wraps constituting the partition from the start side to the end side of the partition in units of laps is the same as the processing in step S103 described in the first embodiment. Therefore, detailed description is omitted.
The addition of data to the updated partition is the same as in the first embodiment described above, and new data can be freely written to the reconstructed partition.

  It should be noted that the processing in steps S402 to S403 by the CPU 6 as the partition restructuring means is not executed unless the command determination means detects the input of the data storage area expansion command from the host device 4, so that the logical configuration of the partition is naturally the same as before. Will be held in the same state.

  Through the above processing, the storage area of the magnetic tape 2 is divided into a content area and an index area, and the data body including various files is stored in the content area, while the data body in the content area can be handled. Even in a situation where the LTFS format for storing the index information in the index area is used as it is, the contents of the index information stored in the index area 72 and the contents area 71 are stored. Data that remains as an overwritable area at the end of a logical partition by cyclically shifting the wrap that makes up the partition from the start to the end of the partition in units of wraps without causing any inconsistency with the contents of the data body Without dividing data while increasing the storage area sequentially It becomes possible to memorize | store cyclically on a magnetic tape.

  In addition, since the LTFS format can be used as it is, it is necessary to make a special modification to the software of the host device 4 even when a configuration in which the magnetic tape 2 is cyclically stored is applied. There is no.

  Under the situation where the LTFS format is used, the host device 4 controls the writing and reading of data with reference to the index information stored in the index area 72 on the magnetic tape 2, but the logical logic of the partition. When updating the configuration, the index information of the part corresponding to the data body stored in the starting wrap of the previous partition is appropriately deleted from the index information and stored in the next wrap, that is, the starting wrap of the updated partition. Since the block ID of the first data block is stored in the index area 72 together with the undeleted index information as a valid block ID, the index information corresponding to the data body invalidated when the partition is reconstructed Appropriate from the latest index area 72 When the data main body is accessed using the index information of the magnetic tape 2, the malfunction of trying to move the magnetic head 5 to the invalid data storage area or the wrong data storage area will occur. Can be prevented.

  In data management using LTFS, generally, data recorded by a write operation to one content area 71 and one index area 72 is defined as data for one generation, and multiple additions are made. If performed, a plurality of generations of data are recorded on the magnetic tape 2. In other words, the generation here is irrelevant to the new and old data by backup, modify, etc., and even if it is another type of data body with completely different contents, the data of the first generation, second generation, third generation,. Sometimes called.

  As already described, the index information of the latest index area 72 describes the index information required for specifying the data body written in the latest generation and the content area 71 of the generation before that. Therefore, normally, if only the latest index information is used, it is possible to access necessary data bodies including those of the previous generation.

  However, when specific data recorded on the magnetic tape 2 is deleted or overwritten, more strictly, the index information of the portion corresponding to the data body to be deleted or overwritten is updated to the latest index. In the case of discarding from the information, there is a problem that even if the data body itself remains on the magnetic tape 2 as magnetic recording, the old generation data body cannot be accessed from the latest index information. On the other hand, there is a request to access these old data bodies.

  In view of these circumstances, a rollback process for accessing the data body based on the previous generation index information will be described with reference to FIG.

  When a read command for index information designating one or more generations of index information to be searched is input from the host device 4 to the magnetic tape device 1, the microprocessor 6 functioning as index information validity determination means first A valid BlockID 725 stored in the latest index area 72 (for example, the index area 72 located at the right end in FIG. 8) on the magnetic tape 2 by driving and controlling a magnetic tape feeding mechanism and a seek mechanism (not shown) and the magnetic head 5. Value, that is, the block ID value of the block storing the first data that has not been invalidated at the present time, and the block ID value at the storage start position of the index information one generation before is also detected (step S501).

  Next, the microprocessor 6 functioning as index information validity determination means determines whether or not the block ID value at the storage start position of the index information of the previous generation is equal to or greater than the effective Block ID 725, that is, the previous generation of the index information. It is determined whether or not the index information (for example, the index information of the index area 72 located second from the right in FIG. 8) is valid (step S502).

  If the block ID value at the storage start position of the index information of the previous generation is greater than or equal to the valid Block ID 725 and the determination result in step S502 is true, that is, the index information of the previous generation is valid. When the determination is made, the microprocessor 6 functioning as the coincidence / non-coincidence determining means further drives and controls the magnetic tape feeding mechanism and seek mechanism (not shown) and the magnetic head 5 to the storage start position of the index information one generation before. By positioning the magnetic head 5, index information of the previous generation stored in the index area 72 of the previous generation (for example, the index area 72 positioned second from the right in FIG. 8) is stored internally, that is, , Read without informing the host device 4. At this time, the microprocessor 6 relatively sets the block ID value at the storage start position of the index information of the previous generation to the index area 72 of the previous generation (for example, the index area positioned second from the right in FIG. 8). 72) and temporarily stored for later determination processing (step S503).

  Then, the microprocessor 6 functioning as the coincidence / non-coincidence determining unit determines whether or not the index information read in the process of step S503 matches the index information designated by the host device 4. (Step S504).

If the determination result in step S504 is false and it is clear that the index information of the previous generation does not match the index information designated by the higher-level device 4, the index information validity determination means and the match / mismatch determination The microprocessor 6 functioning as a means repeatedly executes the processing of steps S502 to S504 in the same manner as described above until the determination result of step S502 is false or the determination result of step S504 is true. Specifically, the block ID at the recording start position of the index information one generation before and the contents of this index information are detected retrospectively in time series.
At this time, the block ID value temporarily stored in the process of step S503 performed immediately before is used as the block ID value of the storage start position of the index information one generation before used in the determination process of step S502.

  In this way, when the determination result of step S502 becomes false while repeatedly executing the processing of step S502 to step S504, that is, the index information validity determination unit without the match / mismatch determination unit determining match. If it is determined that the value of the block ID at the recording start position of the index information detected by the above is less than the value of the valid block ID 725 stored together with the latest index information, the index specified by the host device 4 The index information that matches the information has not been found on the magnetic tape 2 by this time, and the index information of the previous generation has been invalidated by the movement of the partition or does not originally exist. Means.

  Therefore, in this case, the microprocessor 6 functioning as the output information limiting unit transmits an index information read error to the higher-level device 4 and terminates the processing related to reading the index information as it is.

  On the other hand, if the determination result of step S504 becomes true while the processing of step S502 to step S504 is repeatedly executed, that is, if the coincidence / mismatch determination means determines coincidence, it is executed immediately before this. This means that the index information read in the process of step S503 is index information that matches the index information specified by the host apparatus 4.

  Therefore, in this case, the microprocessor 6 functioning as the output information restriction unit, the value of the valid block ID 725 read out in the process of step S501, that is, the value of the valid block ID 725 stored together with the latest index information, Each data included in the index information (for example, the index information of the index area 72 which is second from the right in FIG. 8 and located at the right end in FIG. 7) temporarily stored in the process of step S503 executed immediately before. An index having a block ID 722 less than the value of the valid block ID 725 stored together with the latest index information, by comparing all the magnitude relationships with the value of the block ID 722 of the data block at each reading start position corresponding to the name 721 Information, ie corresponding data body has already been invalidated The other index information excluding these, that is, the index information in which the data body is still valid at the present time is transmitted to the upper level apparatus 4 (step S505).

  Therefore, if the index information designated by the host device 4 is one generation before, the index information in the index area 72 located second from the right in FIG. 8 and at the right end in FIG. The value M of the block ID 722 and the data name 721 of the data block at the read start position corresponding to the data body whose data name 721 is FileA are internally read in the process of step S503 as matching with the specified condition. Only the value M + 1 of the block ID 722 of the data block at the reading start position corresponding to the data body is the effective block ID 725 stored together with the value of the effective block ID 725 read out in the process of step S501, that is, the latest index information. Corresponding to the data body whose data name 721 is FileC. Corresponds to the value M + 3 of the block ID 722 of the data block of the data start position and the value N of the block ID 722 and the data body of the data name 721 corresponding to the data body whose data name 721 is FileD. If the value N + 1 of the block ID 722 of the data block at the read start position to be read is equal to or greater than the value of the valid block ID 725 read in the process of step S501, the data 721 to 7224 related to FileA in this index information. And the data 721 to 722 related to FileB are filtered, and the remaining index information, that is, the data 721 to 7224 related to FileC, the data 721 to 7224 related to FileD, and the data 721 to 7224 related to FileE are stored in the host device 4. Will be sent.

As described above, the magnetic tape device 1 that has received the index information read command from the higher-level device 4 uses the functions of the index information validity determination unit and the coincidence / non-match determination unit to go back in time sequence from the latest index information. Since the contents of the generation index information can be searched, the old generation data body cannot be accessed from the latest index information even if the data body itself remains on the magnetic tape 2 as magnetic recording. Even in such a case, by using the index information finally extracted by the match / mismatch determination means, it becomes possible to appropriately access the data body of the old generation.
In addition, in the case where the index information remains in the index area 72 but the data body of the pot that should be in the content area 71 has been invalidated, it is invalidated by the filtering function of the output information restriction means. Since the index information corresponding to the converted data body, in particular, the value of the block ID 722 indicating the read start position of the invalidated data body is not transmitted to the host device 4, the LTFS writing format is used. Even in a situation where the data is managed, the partition information can be appropriately partitioned without causing inconsistency between the index information stored in the index area 72 and the contents of the data body stored in the content area 71. The reconstruction process can be performed.

  The basic configuration of processing operations in the magnetic tape device 1, that is, the wraps constituting the partition are cyclically shifted from the start side to the end side of the partition in units of laps, and the logical configuration of the partition is updated to make new data cyclic Since the point to be written to is exactly the same as in the first embodiment, the other operations and effects are exactly the same as in the case of the first embodiment.

  A part or all of the embodiment disclosed above can be appropriately expressed by the description shown in the following supplementary notes, but the form for carrying out the invention and the technical idea of the invention are not limited to these. Absent.

  Further, the magnetic tape device control program may be stored in a non-temporary recording medium. As the non-temporary recording medium, for example, a DVD, CD, flash memory or the like can be used. When the magnetic tape device control program is stored in a non-temporary recording medium, the magnetic tape device control program is installed in the nonvolatile memory 7 from the non-temporary recording medium via an appropriate interface, and the magnetic tape device 1 It will be executed by the microprocessor 6.

[Appendix 1]
A method for controlling a magnetic tape device, wherein data is overwritten and stored in a logical partition composed of a plurality of wraps of a magnetic tape,
Determining whether or not the capacity of the data storage area remaining as an overwritable area on the end side of the partition when writing data to the partition exceeds a preset storage capacity;
If the capacity of the data storage area remaining as an overwritable area at the end of the partition exceeds the preset storage capacity, while maintaining the logical configuration of the partition and continuing to write new data,
If the capacity of the data storage area remaining as the overwritable area on the end side of the partition does not exceed the preset storage capacity, the wraps constituting the partition are cyclically shifted from the partition start side to the end side in units of laps. A method of controlling a magnetic tape device, characterized by continuing to write new data after updating the logical configuration of the partition.

[Appendix 2]
The block ID of the first data block of the wrap newly started at the time of updating the logical configuration of the partition is stored in the nonvolatile memory of the magnetic tape cartridge,
Compare the block ID value specified by the positioning command of the magnetic head given from the host device and the block ID value stored in the nonvolatile memory,
If the block ID value specified by the positioning command is equal to or greater than the block ID value stored in the nonvolatile memory, the magnetic head is positioned at the block ID position specified by the magnetic head positioning command.
If the block ID value specified by the positioning command is less than the block ID value stored in the non-volatile memory, the magnetic head is positioned at the wrap that is currently the start of the partition. The method for controlling a magnetic tape device according to appendix 1.

[Appendix 3]
A method for controlling a magnetic tape device, in which index information including a data main body and a read start position of the data main body is overwritten and stored in a logical partition constituted by a plurality of wraps included in the magnetic tape,
Determining whether it is necessary to expand the data storage area remaining as an overwritable area on the end side of the partition when writing the data body and index information to the partition;
If it is not necessary to expand the data storage area, while maintaining the logical configuration of the partition and continuing to write new data body and index information,
If it is necessary to expand the data storage area, the index information corresponding to the data body stored in the starting wrap constituting the partition is deleted, and the block ID of the first data block of the next wrap is valid. The data is stored together with undeleted index information as an ID, and the wraps constituting the partition are cyclically shifted from the start side to the end side of the partition in units of laps, and the logical structure of the partition is updated and a new data body and index are updated. A method of controlling a magnetic tape device, characterized by continuing to write information.

[Appendix 4]
When a read command for index information one or more generations before is given from the host device, the block ID value of the index information is detected in a time series from the previous generation in order,
Each time a block ID of the index information is detected, it is determined whether or not the block ID value is greater than or equal to the valid block ID value stored with the latest index information, and stored with the latest index information. If it is equal to or greater than the valid block ID value, it is further determined whether or not the index information matches the index information given by the read command from the host device. Performs internal reading of information, compares the value of the effective block ID stored together with the latest index information and the size of each read start position included in the matched index information, and updates the latest index information. Index corresponding to data body with read start position less than valid block ID value stored with While allowing the reading of the index information except the information to the host device,
The index information detected by going back in time series does not match the index information given by the read command from the host device, and the block ID value of the detected index information is stored together with the latest index information. 4. The method for controlling a magnetic tape device according to appendix 3, wherein when the value is less than a valid block ID value, reading of the index information is not executed, and a reading error of the index information is notified to the host device.

[Appendix 5]
A magnetic tape device for overwriting data in a logical partition composed of a plurality of wraps of a magnetic tape and storing the data cyclically,
Remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition when writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as the overwritable area exceeds the preset storage capacity, the logical configuration of the partition is maintained while the remaining storage area is maintained. When it is determined by the area determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is circulated in units of laps on the partition start side. And a partition restructuring means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge;
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. And a positioning control means for positioning a magnetic head in a partition in which a lap number is stored as a starting end of the partition in the nonvolatile memory when the block ID is less than the block ID value.

[Appendix 6]
A magnetic tape device that overwrites and stores index information including a data body and a read start position of the data body in a logical partition constituted by a plurality of wraps of the magnetic tape,
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side, and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Each time, the index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched,
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While the apparatus permits, the validity of the block ID value of the index information detected by the index information validity determination means stored together with the latest index information without the match / mismatch determination means determining a match. If it is determined that the block ID is less than Magnetic tape apparatus is characterized in that an output information limiting means for informing the reading of broadcast to the host device a read error of the index information as a non-executable.

[Appendix 7]
A microprocessor provided in a magnetic tape device for overwriting data in a logical partition constituted by a plurality of wraps of the magnetic tape and storing the data in a circular manner;
A remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition at the time of writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as the overwritable area exceeds the preset storage capacity, the logical configuration of the partition is maintained while the remaining storage area is maintained. When it is determined by the area determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is circulated in units of laps on the partition start side. A partition restructuring means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge; and
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. If the value is less than the block ID value, the magnetic tape device control functioning as a positioning control means for positioning the magnetic head in the partition in which the lap number is stored as the start of the partition in the nonvolatile memory. program.

[Appendix 8]
A microprocessor included in a magnetic tape device that overwrites and stores index information including a data main body and a reading start position of the data main body in a logical partition constituted by a plurality of wraps included in the magnetic tape,
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information each time,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched, and
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While permitting the apparatus, the block ID value of the index information detected by the index information validity determining unit is stored together with the latest index information without the matching / non-matching determining unit determining a match. If it is determined that the value is less than the valid block ID value, the index Magnetic tape device control program, characterized in that to function reading error of the index information as output information limiting means for notifying the host device to read the information as non-executable.

  The present invention can be applied to various magnetic tape apparatuses that record data on a magnetic tape having a plurality of wraps.

DESCRIPTION OF SYMBOLS 1 Magnetic tape apparatus 2 Magnetic tape 3 Cartridge 4 High-order apparatus 5 Magnetic head 6 Microprocessor (Remaining storage area determination means, Partition reconstruction means, Partition information update means, Positioning control means, Command determination means, Index information validity determination means, Match / mismatch determination means, output information restriction means)
7 Nonvolatile memory 8 Nonvolatile memory (cartridge memory)
9 Interface 71 Content Area 72 on Magnetic Tape Index Area 311 on Magnetic Tape BOP Position Information Storage Area 312 of Cartridge Memory EOP Position Information Storage Area 313 of Cartridge Memory BOP Block ID Storage Area 314 of Cartridge Memory EOD Block ID of Cartridge Memory Storage area 721 Data name (file name)
722 Read start position (block ID of data block to be read start position)
723 Start offset 724 Data size (data length)
725 Valid Block ID value

Claims (8)

A method for controlling a magnetic tape device, wherein data is overwritten and stored in a logical partition composed of a plurality of wraps of a magnetic tape,
Determining whether or not the capacity of the data storage area remaining as an overwritable area on the end side of the partition when writing data to the partition exceeds a preset storage capacity;
If the capacity of the data storage area remaining as an overwritable area at the end of the partition exceeds the preset storage capacity, while maintaining the logical configuration of the partition and continuing to write new data,
If the capacity of the data storage area remaining as the overwritable area on the end side of the partition does not exceed the preset storage capacity, the wraps constituting the partition are cyclically shifted from the partition start side to the end side in units of laps. A method of controlling a magnetic tape device, characterized by continuing to write new data after updating the logical configuration of the partition. The block ID of the first data block of the wrap newly started at the time of updating the logical configuration of the partition is stored in the nonvolatile memory of the magnetic tape cartridge,
Compare the block ID value specified by the positioning command of the magnetic head given from the host device and the block ID value stored in the nonvolatile memory,
If the block ID value specified by the positioning command is equal to or greater than the block ID value stored in the nonvolatile memory, the magnetic head is positioned at the block ID position specified by the magnetic head positioning command.
If the block ID value specified by the positioning command is less than the block ID value stored in the non-volatile memory, the magnetic head is positioned at the wrap that is currently the start of the partition. The method of controlling a magnetic tape apparatus according to claim 1. A method for controlling a magnetic tape device, in which index information including a data main body and a read start position of the data main body is overwritten and stored in a logical partition constituted by a plurality of wraps included in the magnetic tape,
Determining whether it is necessary to expand the data storage area remaining as an overwritable area on the end side of the partition when writing the data body and index information to the partition;
If it is not necessary to expand the data storage area, while maintaining the logical configuration of the partition and continuing to write new data body and index information,
If it is necessary to expand the data storage area, the index information corresponding to the data body stored in the starting wrap constituting the partition is deleted, and the block ID of the first data block of the next wrap is valid. The data is stored together with undeleted index information as an ID, and the wraps constituting the partition are cyclically shifted from the start side to the end side of the partition in units of laps, and the logical structure of the partition is updated and a new data body and index are updated. A method of controlling a magnetic tape device, characterized by continuing to write information. When a read command for index information one or more generations before is given from the host device, the block ID value of the index information is detected in a time series from the previous generation in order,
Each time a block ID of the index information is detected, it is determined whether or not the block ID value is greater than or equal to the valid block ID value stored with the latest index information, and stored with the latest index information. If it is equal to or greater than the valid block ID value, it is further determined whether or not the index information matches the index information given by the read command from the host device. Performs internal reading of information, compares the value of the effective block ID stored together with the latest index information and the size of each read start position included in the matched index information, and updates the latest index information. Index corresponding to data body with read start position less than valid block ID value stored with While allowing the reading of the index information except the information to the host device,
The index information detected by going back in time series does not match the index information given by the read command from the host device, and the block ID value of the detected index information is stored together with the latest index information. 4. The method of controlling a magnetic tape device according to claim 3, wherein, when the value is less than a valid block ID value, reading of the index information is not executed and an error in reading the index information is notified to the host device. A magnetic tape device for overwriting data in a logical partition composed of a plurality of wraps of a magnetic tape and storing the data cyclically,
Remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition when writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as the overwritable area exceeds the preset storage capacity, the logical configuration of the partition is maintained while the remaining storage area is maintained. When it is determined by the area determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is circulated in units of laps on the partition start side. And a partition restructuring means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge;
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. And a positioning control means for positioning a magnetic head in a partition in which a lap number is stored as a starting end of the partition in the nonvolatile memory when the block ID is less than the block ID value. A magnetic tape device that overwrites and stores index information including a data body and a read start position of the data body in a logical partition constituted by a plurality of wraps of the magnetic tape,
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side, and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Each time, the index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched,
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While the apparatus permits, the validity of the block ID value of the index information detected by the index information validity determination means stored together with the latest index information without the match / mismatch determination means determining a match. If it is determined that the block ID is less than Magnetic tape apparatus is characterized in that an output information limiting means for informing the reading of broadcast to the host device a read error of the index information as a non-executable. A microprocessor provided in a magnetic tape device for overwriting data in a logical partition constituted by a plurality of wraps of the magnetic tape and storing the data in a circular manner;
A remaining storage area determination means for determining whether or not the capacity of the data storage area remaining as an overwritable area on the terminal end side of the partition at the time of writing data to the partition exceeds a preset storage capacity;
When the remaining storage area determination unit determines that the capacity of the data storage area remaining as an overwritable area exceeds a preset storage capacity, the logical structure of the partition is maintained, while the remaining storage area When it is determined by the determination means that the capacity of the data storage area remaining as the overwritable area does not exceed the preset storage capacity, the wrap constituting the partition is cyclically terminated from the partition start end side in units of laps. Partition rebuilding means for updating the logical configuration of the partition,
At least the wrap number of the wrap updated by the partition rebuilding means, the wrap number of the wrap updated by the partition rebuilding means, and the partition rebuilding means Partition information updating means for updating and storing the block ID of the first data block of the wrap which is the start of the partition updated by the non-volatile memory of the magnetic tape cartridge; and
The block ID value specified by the positioning command of the magnetic head given from the host device is compared with the block ID value stored in the nonvolatile memory, and the block ID value specified by the positioning command is If the value is equal to or greater than the block ID value stored in the memory, the magnetic head is positioned at the block ID position specified by the positioning command, while the block ID value specified by the positioning command is stored in the nonvolatile memory. If the value is less than the block ID value, the magnetic tape device control functioning as a positioning control means for positioning the magnetic head in the partition in which the lap number is stored as the start of the partition in the nonvolatile memory. program. A microprocessor included in a magnetic tape device that overwrites and stores index information including a data main body and a reading start position of the data main body in a logical partition constituted by a plurality of wraps included in the magnetic tape,
Command determination means for determining whether or not a data storage area expansion command is input from the host device;
If the command determination means does not detect the input of the data storage area expansion command, the logical configuration of the partition is maintained. On the other hand, if the command determination means detects the input of the data storage area expansion command, the partition is configured. Delete the index information corresponding to the data body stored in the starting wrap, store the block ID of the first data block of the next wrap as a valid block ID together with the undeleted index information, and store the partition Partition reconstructing means for cyclically shifting the wrap to be configured in units of laps from the partition start side to the end side and updating the logical configuration of the partition;
When a read command for index information of one generation or more before is given from the host device, the block ID value of the index information is detected by going back in time sequence from the previous generation, and the block ID of the index information is detected. Index information validity determination means for determining whether the value of the block ID is equal to or greater than the value of the valid block ID stored together with the latest index information each time,
When it is determined that the block ID of the index information detected by the index information validity determination means is equal to or greater than the value of the valid block ID stored together with the latest index information, the index information is sent from the host device. A match / mismatch determination means for determining whether or not the index information given by the read command is matched, and
When the coincidence / non-coincidence judging unit judges coincidence, the index information is internally read and included in the index information that matches the valid block ID value stored together with the latest index information. Compares the size with each of the read start positions, and reads the index information excluding the index information corresponding to the data body having the read start position less than the valid block ID value stored together with the latest index information. While permitting the apparatus, the block ID value of the index information detected by the index information validity determining unit is stored together with the latest index information without the matching / non-matching determining unit determining a match. If it is determined that the value is less than the valid block ID value, the index Magnetic tape device control program, characterized in that to function reading error of the index information as output information limiting means for notifying the host device to read the information as non-executable.

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