JP4759609B2 - Tape drive control device and tape drive control method - Google Patents

Description

  The present invention relates to a tape drive control apparatus and a tape drive control method for controlling access to a file written on a magnetic tape medium.

  In a magnetic tape storage device, to write or read a file, the tape medium is moved and the head is positioned at a desired position on the tape. When reading a file, the tape head is positioned at the head of the file to be read and then the file is read. Positioning the tape head at the beginning of a file to access the file is called seeking. In addition, the distance that the head moves by the seek operation is called a seek distance, and the time required for the head to move the seek distance is called a seek time. In order to improve the file reading performance, it is necessary to shorten the seek time.

  In the linear recording method before the LTO (Linear Tape-Open) standard was proposed, the file on the tape medium is from the physical front end (BOT: Beginning Of Tape) to the end (EOT: End Of Tape) of the tape. The files are arranged in the ascending order of the file numbers through the file marks indicating between the files. When a request to read multiple files occurs for a large number of files on a tape medium, instead of reading the files in the order in which they were requested, reading the files in ascending order of the file numbers enabled them to be read quickly. .

  However, in a tape compliant with the LTO standard, when a data file is written from BOT to EOT, the data file is folded back at EOT and written from EOT to BOT. Further, when the file is written up to the BOT, it is folded back at the BOT and written toward the EOT. If there is a file recorded from EOT to BOT on the tape, it cannot be read efficiently by simply reading in ascending order of the file numbers.

  When there is a random access request to the tape medium, the reordering unit compares the position of the head position of all data with the current magnetic head every time the read / write process is completed, It is known to select the one with the shortest distance. It is also known to reduce the average data access time by placing the magnetic head at the midpoint of the data storage area of the magnetic tape when the tape is loaded into the drive device. (See Patent Documents 1 and 2)

JP 2000-48549 A JP 2004-355747 A

  In view of the above problems, an object of the present invention is to provide a tape drive control device and a tape drive control method capable of improving access efficiency to a file by a learning function.

  The tape drive control device is a seek management table in which seek information including a seek time or seek distance from a tape head position to a file head position is registered in the order of written files, and the seek information is determined. The confirmed seek information is registered for the information confirmed file, and the seek information for which the seek information is not confirmed for the seek information unconfirmed file is written before the file and the seek of the file for which the seek information is confirmed. When the information is temporarily registered and then seek information of the seek information unconfirmed file is confirmed, the seek management table in which the confirmed seek information is registered, the head is positioned at a desired position on the tape, and data is written or read by the head Tape running control unit that controls the tape running so that The tape running control unit extracts, from the seek management table, seek times or seek distances of the plurality of files having the read request in response to the read requests of the plurality of files written discretely. The tape travel is controlled so as to access the plurality of files requested to be read in ascending order of the extracted seek time or seek distance.

  The tape drive control method is a tape drive control method in a tape drive control device including the seek management table and the tape travel control unit, wherein the tape travel control unit includes a plurality of files written discretely. In response to the read request, the seek time or seek distance of a plurality of files having the read request is extracted from the seek management table, and the head performs the read request in ascending order of the extracted seek time or seek distance. Controls tape travel to access multiple files.

  In the tape drive control device and the tape drive control method, it is preferable to read in ascending order of file numbers in response to a read request for a plurality of files written successively.

  Since the seek management table used by the tape drive control apparatus and the tape drive control method can learn the seek time or seek distance to a file, efficient file access can be achieved.

  First, a file access method on a tape medium which is recorded by being folded back by EOT and BOT will be described. In the tape recording apparatus, the tape head is at a fixed position, and the tape moves to position a desired position on the tape with respect to the tape head. However, in the following description, in order to simplify the description, it may be described that the tape head moves with respect to the tape.

(Access to multiple files written discretely)
FIG. 1 is a diagram for explaining a reading method when files requested to be read are scattered on the tape. FIG. 1 shows the position of a file on the tape by unfolding the tape 10 from the physical tape front end (BOT) to the end end (EOT). Furthermore, a seek operation and a read operation are shown as the movement of the tape head 20.

  The numbers above the files F # 1 to F # 5 in FIG. 1 indicate the seek time from the BOT to the beginning of the file. In FIG. 1, the beginning of the file is indicated by a vertical double line. The seek times of the files F # 1 to F # 5 are 1 second for the file F # 1, 180 seconds for the file F # 2, 90 seconds for the file F # 3, 50 seconds for the file F # 4, and the file F # 5. Then it is 110 seconds.

  The head operation A in FIG. 1 shows the head movement when reading the files F # 1 to F # 5 in ascending order of the file numbers. The head operation B in FIG. 1 shows the head movement when reading the files F # 1 to F # 5 in ascending order of the seek time of the file. In both cases, the broken arrow indicates the movement of the tape head by seeking, and the solid arrow indicates the movement of the head by reading.

When the files F # 1 to F # 5 are read in ascending order of the file numbers shown in the head operation A of FIG. 1, the seek time (seconds) for reading all the files is approximately as follows.
1+ (180-1) + (180-90) + (90-50) + (110-50)
= 370

Ascending order of seek time shown in head operation B of FIG. 1, that is, seek time for reading all files if reading is performed in the order of F # 1, F # 4, F # 3, F # 5, and F # 2. (Seconds) is approximately as follows.
1+ (50-1) + (90-50) + (110-90) + (180-110)
= 180

  In the example shown in FIG. 1, when a file is read in ascending order of file numbers, the total seek time takes approximately 370 seconds, and when a file is read in ascending order of seek time, the total seek time is approximately 180 seconds. If access to a plurality of files scattered on the folded track is read in ascending order of seek time from the BOT, the moving distance of the tape head can be shortened and the total seek time can be shortened.

(Access to consecutive files)
FIG. 2 is a diagram for explaining an access method for files continuously recorded on a backward track on a tape. 2 also shows the tape 10 expanded from BOT to EOT as in FIG. 1, and the movement of the head 20 will explain the relative movement of the tape and the head.

  Even when the files on the tape are continuously accessed as shown in FIG. 2, it is advantageous if it is efficient to read in ascending order of seek time as in FIG. However, as shown in FIG. 2, when the files F # 1 to F # 4 are continuously arranged in the backward track, that is, in the direction from BOT to EOT, it is efficient to read in ascending order of seek time. is not.

  Head operation A in FIG. 2 shows head movement when reading F # 4 → F # 3 → F # 2 → F # 1 in ascending order of seek time. In the head operation A, the head seek operation indicated by the broken line and the head read operation indicated by the solid line partially overlap, and the head movement is not efficient.

  On the other hand, the head operation B in FIG. 2 shows a case where F # 1 → F # 2 → F # 3 → F # 4 are read in ascending order of file numbers. In FIG. 2, when head operation A and head operation B are compared, it is apparent that head operation B that reads in ascending order of file numbers is more efficient.

  In addition, it is known that it is efficient to read out files in a continuous forward track in ascending order of file numbers. Furthermore, it is efficient to read a file that continues from the forward track to the backward track or from the backward track to the forward track in ascending order of the file numbers.

  From the above considerations, it is efficient to read multiple files that are discrete on the tape in ascending order of seek time, and multiple files that are continuous on the tape are efficient to read in ascending order of file numbers. Can do.

  In order to read a plurality of files scattered on the tape in ascending order of seek time, it is conceivable to calculate and store the seek time or seek distance from the BOT to the beginning of the file in advance. For example, if the seek time or seek distance is calculated and stored based on the file size to be written, it is easy to arrange a plurality of files in ascending order of seek time.

  However, in the LTO standard, data is compressed by a tape drive and written onto a tape medium. Further, processing is performed so that data is not written in the magnetic material abnormality portion of the tape medium. Therefore, even if the file size is the same without being written to the tape medium, the file size may change when written to the tape medium. Therefore, it is generally impossible to calculate the seek distance and hence the seek time from the file size before being written on the tape medium.

  In this embodiment, a seek management table for managing the seek time from the BOT to the beginning of the file for the written file is provided, and if the seek time can be measured when writing the file, the seek time is recorded. A temporary seek time is recorded for a file whose seek time cannot be measured at the time of writing. Thereafter, if there is an opportunity to actually measure the seek time by an access operation to a file having a temporary seek time, the temporary seek time is corrected to a true seek time. In this way, the most efficient file access is achieved while completing the table. In other words, in the present embodiment, file access is efficiently performed based on the seek time learned by the tape controller itself.

  FIG. 3 is an example of a seek management table for managing the seek time from the BOT of the file on the tape. In this embodiment, the seek time is managed by the seek management table, but the seek distance may be managed instead of the seek time.

  The seek management table 30 includes a file number column 31, a seek time column 33, a recording direction column 35, and a fix value column 37. In the file number column 31, file numbers are recorded in the order written on the tape. In the seek time column 33, the seek time required to move the head from the BOT to the head position of the file is recorded in seconds. In the recording direction column 35, the recording direction of the file is recorded. When the file is recorded from the BOT to the EOT of the tape, the forward direction is registered. When the file is recorded from EOT to BOT on the tape, the backward direction is registered. In the fix value column 37, a value indicating whether the seek time in the seek time column 33 is determined or not yet determined is recorded. When the seek time recorded in the seek time column 33 is actually measured, True indicating that it is a definite value is recorded. If the seek time recorded in the seek time column 33 is not actually measured, False indicating that it is a temporary value is recorded.

  In the seek management table 30 in FIG. 3, since the fix values of all the registered files are True, it indicates that the seek time of the file is fixed. For example, the file with the file number 3 has a seek time of 100 seconds and the reading direction is the forward direction. The file with the file number 5 has a seek time of 100 seconds and the reading direction is the forward direction.

  When the seek management table 30 shown in FIG. 3 is stored in a storage device such as a semiconductor memory or a hard disk of the tape drive control device, the plurality of files are sought in response to a plurality of file read requests from the host device. Control can be performed so that the data are read out in the ascending order of time.

  Next, an example of the tape drive control device of the present embodiment and an example of a seek management table generation process will be described with reference to FIGS.

  FIG. 4 is a diagram showing an outline of one track of the tape and the tape drive control device. The tape drive control device 1 includes a tape drive control unit 2, a write / read control unit 4, and a storage device 3 having a seek management table 30. The tape running control unit 2 executes running control such as feeding and rewinding of the tape medium 10. The writing / reading control unit 4 executes data writing / reading on the tape medium 10 by the head 20. When there is a read request for a plurality of files from the host device 40, the tape running control unit 2 refers to the seek management table stored in the storage unit 3 in response to this and the plurality of files for which a read request has been made Control access to.

  In the tape medium 10 of the present embodiment, information to be newly written is added as a new file after the already written file. In FIG. 4, the files F # 1 to F # 3 are written on one track of the tape together with the file mark FM indicating the end of the file, and the files F # 4 to F # 6 are in a state to be additionally written.

  The tape running control unit 2 seeks the tape medium from the BOT to the next writing position of the file mark FM indicating the end of the file F # 3. At this time, the seek time is measured to be 150 seconds. The head 20 writes the file F # 4 from the seek position on the tape medium 10. When the writing to the file F # 4 is completed, after writing the file mark FM, the file F # 5 is continuously written, and the file F # 6 is similarly written.

  FIG. 5 is a diagram showing data recorded in the seek management table when the file shown in FIG. 4 is added. Prior to the additional writing of file F # 4, data up to file number 30 has already been stored. For example, the seek time of file F # 3 is registered as 100 seconds, the recording direction is forward, and the fix value is True.

  As a result of the additional writing of the file F # 4, 150 seconds, which is an actually measured seek time, is recorded in the seek time column 33 corresponding to the file number 4. The seek time of file number 4 150 seconds is longer than the seek time 100 of file number 3. Therefore, the recording direction of file number 4 is determined to be the same as the recording direction of file number 3. In the recording direction column 35, the same forward as the file number 3 is recorded. In the fix value column 37, True is recorded because the seek time of file number 4 is fixed 150 seconds.

  Following file number 4, seek data of file F # 5 and file F # 6 are recorded in file numbers 5 and 6, respectively. However, since the file F # 5 and the file F # 6 are continuously written to the file F # 4, their seek times are unknown. In this case, the seek time column 33 corresponding to the file numbers 5 and 6 records the same seek time 150 seconds as the file number 4 as a temporary seek time. In the recording direction column 35 corresponding to the file numbers 5 and 6, the same direction as the file number 4 is recorded as a temporary direction. Then, False indicating that the file numbers 5 and 6 are unconfirmed is registered in the fix value column.

  FIG. 6 is a diagram illustrating an example of correction of the seek management table of FIG. Assume that there is a read request for file F # 5 in FIG. 4 after generation of seek management table 30 in FIG. As a result, the head 20 is sought from the BOT to the head of the file F # 5. The seek time is 160 seconds in actual measurement.

  As shown in the seek management table 30 of FIG. 6, the seek time column 37 of the file number 5 is changed from 150 seconds to 160 seconds. Since the seek time of file number 5 is 160 seconds longer than the seek time of file number 4, the recording direction remains forward. Since the seek time of file number 5 is actually measured and fixed, the fix value of file number 5 changes to True.

  For the file F # 6, since the seek time is not fixed, the fix value remains False. However, since the seek time of the file F # 5 is fixed at 160 seconds, the seek time of the file F # 6 is also updated to 160 seconds. The direction is forward as before.

  FIG. 6 shows that a specific file is sought from the BOT and read. The seek time for a specific file is obtained, and the temporary data in the seek management table is corrected accordingly, and the seek data for the specific file is confirmed. Similarly, the seek time is determined even when a file having a temporary seek time is rewound from its head position to the BOT. Therefore, even when rewinding from the head position of a specific file to the BOT, the seek time of the specific file is determined, and as a result, the recording direction is also determined. As a result, the temporary data in the seek management table is corrected, and the fix value corresponding to the specific file is changed to True.

  7 to 9 are diagrams illustrating another example of correction of the seek management table. FIG. 7 is a diagram showing a state in which the file F # 12 is accessed after the file F # 10 to the file F # 13 are continuously added. FIG. 8 is a diagram showing the seek management table 30 at the time when the additional writing from the file F # 10 to the file F # 13 is completed. FIG. 9 is a view showing a seek management table corrected by accessing the file F # 12.

  First, when additional writing is continuously performed from file F # 10 to file F # 13, the first file F # 10 is sought from the BOT to the writing position of file F # 10. At this time, the seek time of the file F # 10 was actually measured, and the measurement result was 170 seconds. Therefore, 170 is recorded in the seek time column 33 corresponding to the file number 10 in the seek management table 30 of FIG. In the recording direction column 35, forward is recorded because it is longer than the seek time of the file F # 9 (not shown). Since the seek time is fixed, True is recorded in the fix value column 37.

  However, since the files F # 11 to F # 13 are continuously written, the seek time is not fixed. Therefore, the same seek time and recording direction as those of the file F # 10 are temporarily recorded in the seek management table 30, and the fix value column 37 is set to False.

  Next, as shown in FIG. 7, there is a read request for the file F # 12, and the tape head is sought from the BOT to the head of the file F # 12. At this time, the seek time was 150 seconds. Therefore, 150 seconds is registered in the seek time column corresponding to the file number 12 in the table of FIG. Further, since the seek time of file F # 12 is 150 seconds shorter than the seek time of file F # 10 of 170 seconds, it can be determined that there is a return. Therefore, backward is recorded in the recording direction column 35. Since the seek time of the file number 12 is fixed, the fix value column 37 changes to True. In the corrected seek management table 30, the row corresponding to the file number 12 is True as shown in FIG.

  The file F # 13 subsequent to the file F # 12 is corrected in the same seek time and recording direction as the file F # 12. However, since the seek time and direction of the file F # 13 are not fixed, the fix value remains False.

  The file F # 11 is not corrected this time, as can be seen from the fact that the fix value of the file number 12 in FIG. 9 is False. If the file F # 11 is subsequently accessed, the seek time is fixed and corrected.

  As can be seen from FIG. 7, if the seek time of the file F # 11 is obtained, it may be longer than the seek time of the file F # 10. Therefore, although the file F # 11 is actually written in the backward direction, the recording direction is registered as forward on the seek management table 30. That is, the direction remains forward even if the fix value corresponding to the file number 11 becomes True. However, the seek management table 30 is intended to increase the access efficiency to the file. Therefore, even if the recording direction registered in the seek management table 30 is different from the actual tape direction, there is no problem as long as the access efficiency is improved.

  In the above-described embodiment, the case of seeking from the BOT has been described. In a system that randomly accesses an arbitrary file on the tape, the seek is often performed from a position that is not a BOT to the head position of the file. With reference to FIGS. 10 and 11, a description will be given of a method for correcting a seek management table when seeking from a position that is not a BOT to the head position of a file.

  FIGS. 10A to 10C are diagrams showing an example of correction of the seek management table when accessing the file F # b from the file F # a in the forward track.

  As shown in FIG. 10A, the file F # a is written on the forward track of the tape 10, and then the file F # b is written. As can be seen from the seek management table 30 in FIG. 10B, the seek time of the file F # a is fixed at 60 seconds. However, the seek time column of the file F # b temporarily stores 60 seconds, which is the seek time of the file F # a, and the fix value is False.

  As shown in FIG. 10A, the head 20 is at the head position of the file F # a. Next, in response to a read request for the file F # b, the head 20 seeks from the head position of the file F # a to the head position of the file F # b. It is assumed that this seek time is 20 seconds. Here, referring to the direction information stored in the seek management table 30 in FIG. 10B, the direction information column 35 indicates that both the files F # a and F # b are forward. . Therefore, the seek time from the BOT of the file F # b is calculated by adding 60 seconds + 20 seconds and becomes 80 seconds.

  As a result, as shown in FIG. 10C, the seek time column 33 of the file number b in the seek management table 30 is changed to 80 seconds. However, since the seek time of 80 seconds in this case is not an actual measurement value, the fixture value column 37 of the file number b is not True and False is maintained. The seek time from the file F # bBOT is not a definite value, but is considered to be close to the actual value. Therefore, by using this fixed value of 80 seconds as the seek time from BOT of file F # b, file access can be made efficient. When the seek time from the BOT of the file F # b is actually measured, the actually measured value is stored in the seek time column of the seek time management table 30, and the fix value is changed to True.

  FIGS. 11A to 11C are diagrams showing an example of correction of the seek management table when accessing the file F # d from the file F # c in the backward track.

  As shown in FIG. 11A, the file F # c is written on the backward track of the tape 10, and then the file F # d is written. As can be seen from the seek management table 30 in FIG. 11B, the seek time of the file F # c is fixed at 100 seconds. However, the seek time column of the file F # d temporarily stores 100 seconds, which is the seek time of the file F # c, and the fix value is False.

  As shown in FIG. 11A, the head 20 is at the head position of the file F # c. Next, in response to a read request for the file F # d, the head 20 seeks from the head position of the file F # c to the head position of the file F # d. It is assumed that this seek time is 70 seconds. Referring to the direction column 35 of the seek management table 30 in FIG. 11B, it can be seen that the directions of the files F # c and F # d are backwards. Therefore, the seek time from the BOT of the file F # d is calculated as 100 seconds-70 seconds by subtraction, and becomes 30 seconds.

  As a result, as shown in FIG. 11C, the seek time column 33 of the file number d in the seek management table 30 is changed to 30 seconds. However, since the seek time of 30 seconds in this case is not an actual measurement value, the fixture value column 37 of the file number a is not True and False is maintained. The seek time from the BOT of the file F # d is not fixed, but is considered to be close to the actual value. Therefore, by using the fix value of 30 seconds as the seek time from the BOT of the file F # b and the file F # d, the file access can be made efficient. When the seek time from the BOT of the file F # d is actually measured, the actually measured value is stored in the seek time column of the seek time management table 30, and the fix value is changed to True.

  By using the seek time management table, it is possible to read out the file more efficiently. For example, when reading files placed on a backward track on a tape in ascending order, for example, every other file, use the seek time management table to determine how to read them efficiently. can do.

  FIG. 12 is a diagram illustrating a case where files F # 21, F # 23, and F # 25 are read out of the files F # 21 to F # 26 continuously arranged in the backward track. Note that FM in FIG. 12 is a file mark indicating the end of the file. The file access plan C indicates a case where the file is read in ascending order of seek time from the BOT, and the file access plan D indicates a case where the file is read in ascending order of the file number.

  The time for reading the file indicated by the solid line in FIG. 12 is the same. Therefore, by comparing the seek times indicated by the broken lines in FIG. 12, it is determined which of the access plans C and D is an efficient reading method.

  In FIG. 12, the seek time of the file F # n (1 ≦ n ≦ 6) is indicated by S # n. The seek time S # n is a seek time from the BOT to the beginning of the file F # n. A seek distance may be used instead of the seek time.

The total seek time for Access Plan C is
S # 25 + (S # 23-S # 26) + (S # 21-S # 24)
It becomes. Here, the term (S # 23-S # 26) represents the time during which the head 20 moves on the files F # 25, F # 24, F # 23. The term (S # 21-S # 24) represents the time for the head 20 to move on the files F # 23, F # 22, F # 21.

The total seek time for access plan D is
S # 21 + (S # 22-S # 23) + (S # 24-S # 25)
It becomes. Here, the term (S # 22-S # 23) represents the time during which the head 20 moves on the file F # 22. The term (S # 21-S # 24) represents the time during which the head 20 moves on the file F # 24.

  Therefore, if the seek time of the file immediately after the file to be read is stored as a fix value in the seek time management table, the total seek time of the file access plans C and D can be obtained. Therefore, a more efficient reading method can be determined by comparing the total seek times of the file access plans C and D.

  As described above, in the present embodiment, the seek time is learned by the result of the seek operation for writing or reading the file or the rewind operation, and the seek management table becomes complete as a result of the learning. Therefore, it is not necessary to calculate a seek time in advance and have a complete seek management table.

  As can be seen from the seek management table, a temporary seek time is recorded even if the seek time is not fixed. When accessing an undefined file, a temporary seek time is used. When it is necessary to access a plurality of discrete files having the same seek time, if the recording direction is forward, it can be determined that the seek time is shorter when the file number is smaller. If the recording direction is backward, it can be determined that the seek time is shorter when the file number is larger.

  In addition, when accessing continuously written files, they may be read in ascending order of file numbers regardless of the recording direction.

  Therefore, if the files are arranged in a discrete manner, the file is accessed in the ascending order of the seek time. If the files are arranged continuously, the file is accessed in the ascending order of the seek time. Efficient file access can be achieved. Furthermore, since the file access plan can be evaluated using the seek management table, more efficient file access can be performed.

It is a figure explaining the reading method of the file folded and recorded on the tape. It is a figure explaining the reading method of the file continuously recorded on the backward direction on the tape. It is a figure explaining the seek management table of one embodiment. It is a figure explaining the tape drive control apparatus of one Embodiment. It is a figure which shows an example of the seek management table in which the seek information was registered when the file was added. It is a figure which shows an example of correction | amendment of the seek management table of FIG. It is a figure explaining the reading of the file which causes correction | amendment of a seek management table. It is a figure which shows an example of the seek management table before the file reading of FIG. It is a figure which shows an example of the seek management table after the file reading of FIG. (A) is a figure which shows an example which seeks from a certain file to another file on a forward track, (b) is an example of the file management table when the seek time of one file is decided (C) is a figure which shows an example of the file management table after seeking from one file to another file. (A) is a figure which shows an example which seeks from a certain file to another file on a backward track, (b) is an example of the file management table when the seek time of one file is decided (C) is a figure which shows an example of the file management table after seeking from one file to another file. It is a figure explaining determination of the effective reading method of the file arrange | positioned every other file among the files arrange | positioned continuously on a backward track | truck.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tape medium 20 Head 30 Seek management table 1 Take drive control apparatus 2 Tape travel control part 3 Memory | storage part 4 Write / read control part

Claims (4)

The seek information including seek time or seek distance from the tape head position to the file head position is a seek management table registered for each written file, and the seek information confirmation file for which the seek information is confirmed The seek information is registered, and for the seek information unconfirmed file for which the seek information is not confirmed, the seek information of the file for which seek information is written before the file is confirmed is temporarily registered. A seek management table in which the seek information is registered when the seek information of the seek information undetermined file is confirmed;
A tape running control unit that controls the tape running so that the head is positioned at a desired position on the tape, and data is written or read by the head; and
In response to a read request for a plurality of files written discretely, the tape running control unit extracts a seek time or a seek distance of the plurality of files having the read request from the seek management table, and reads the read request. A tape drive control device for controlling the running of the tape so as to access a plurality of files having the same seek time or seek distance in ascending order.   The tape drive control device according to claim 1, wherein the tape running control unit reads in ascending order of file numbers in response to a read request for a plurality of files written continuously. A seek management table in which seek information including a seek time or seek distance from the tape head position to the file head position is registered in the order of the written file, and the seek information confirmed file for which the seek information is confirmed The fixed seek information is registered, and for the seek information unconfirmed file for which the seek information is not fixed, the seek information of the file that has been written before the file and the seek information is fixed is temporarily registered, A seek management table in which the fixed seek information is registered when the seek information of the seek information unconfirmed file is fixed;
A tape drive control method in a tape drive control device, comprising: a tape travel control unit that controls the tape travel so that the head is positioned at a desired position on the tape and the data is written or read by the head.
The tape running control unit is
In response to a read request of a plurality of files written discretely, a seek time or a seek distance of the plurality of files having the read request is extracted from the seek management table,
A tape drive control method for controlling the tape travel so that the head accesses the plurality of files requested to be read in ascending order of the extracted seek time or seek distance.   4. The tape drive control method according to claim 3, wherein the tape running control unit reads in ascending order of file numbers in response to a read request for a plurality of files written continuously. 5.

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