JPH07176169A - Magnetic tape device control method - Google Patents

Abstract

PURPOSE:To make the maximum value of head movement small by specifying whether a head is to be positioned at a specified position or not at every retrieving of a data set with a head positioning specifying part. CONSTITUTION:When all data are backed up as a data utilizing method, since data are overwritten on a tape from the start of the tape, the positioning of the head is unnecessary. Moreover, when a reproducing procession in which data in a same tape are reproduced randomly or a recording procession in which data are recorded on the tape randomly is requested, the mean positioning time of the head for a data set whose recording and reproducing are requested in next time can be shortened by specifying so that the head is positioned at the midpoint of the tape 6 and by positioning the head at that point with a head positioning part 203.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a medium for recording a plurality of data sets and sequentially reproducing / recording a large amount of data, for example, a tape for a digital video tape recorder (DVTR) or a helical scan system. The present invention relates to a method for controlling a magnetic tape device that positions a head to data recorded on a tape such as a magnetic tape (hereinafter referred to as "magnetic tape" or "tape"), and is particularly suitable for shortening the positioning average time. Magnetic tape device control method.

[0002]

2. Description of the Related Art Recently, the use of a magnetic tape product, which has a large amount of multimedia data and graphic user interface (GUI) data, can store a large amount of data, and is portable and has good cost performance. The range is increasing in the future. Specifically, it can be considered that a large amount of data is stored in a large-capacity tape, brought to a customer, and used in a conference or a presentation to reproduce the data from the tape. On the other hand, large-capacity tapes such as digital audio tape recorders (DAT) and 8 mm tapes have been developed for the conventional cassette magnetic tape and open reel tape data sets. (1) The recording capacity is larger than that of conventional magnetic tapes (references (a) and (b)). (2) Directory information such as positions of a plurality of data sets recorded on the tape is recorded on the tape, and the data set is searched based on this information (references (b) and (c)). . (3) The directory information is not always recorded at the beginning (reference document (c)). (4) High-speed search is possible by feeding the tape at high speed.
Magnetic tapes using the helical scan method can retrieve data about 100 times faster than magnetic tapes (reference (a)). (5) Partial rewriting of data on the tape is possible (reference (a)). (6) Some tapes, such as DAT, can be unloaded without rewinding the tape (reference (a)). Recently, each company is developing products of several tens GB to 100 GB or more, and some of them have already been shipped. [References] (a) Nikkei Byte April 1989 "The first step is magneto-optical, high density FDD, DAT:
DAT for data "(b) Nikkei Electtronics March 7, 1988 n
o. 422 "Format for using DAT for recording code data,
Sony and HP, joint proposal ”(c) Japanese Patent Application No. 03-069197 and Japanese Patent Application No. 04-
No. 073317

[0003]

As described in the above-mentioned prior art, in the future, the recording capacity of the magnetic tape will become larger and larger, and in many cases, a plurality of data sets will be recorded on the same tape before use. It is expected to be. Further, since it is possible to partially rewrite the data on the tape, it is considered that the same tape is often used repeatedly. Normal,
After the reproduction or recording process is completed, the head remains in the same position. However, if multiple data sets on the tape are randomly requested to be reproduced or recorded and the head is left as it is until the next request arrives, the head stays at a position biased toward the head or tail of the tape. there is a possibility. In such a case, it takes time to position the head until the next requested data set. Also, some tapes can be unloaded without rewinding the tape.
Furthermore, the directory information is not always at the beginning of the tape. Therefore, when the tape is loaded, it is necessary to position the head up to the recording position of the directory information of the data set, and it takes extra time. An object of the present invention is to provide a magnetic tape device control method suitable for improving such a problem and shortening the positioning average time to a data set recorded on a medium having a large capacity and recording / reproducing sequentially. To provide. Another object is to efficiently update the directory information in the magnetic tape.

[0004]

[Means for Solving the Problems] To achieve the above object,
According to the magnetic tape device control method of the present invention, the head is located at a specific position (for example, a position corresponding to ½ of the total recording capacity of the data set or the grouped data set or ½ of the magnetic tape length). Specify whether or not to position, and if the next data set to be reproduced / recorded is undecided, position the magnetic head at the specified position, and if the next reproduction / recording request has already arrived, request it. When the tape is unloaded, the directory information (identifiers of multiple data sets recorded on the magnetic tape, data set names, data set recording capacity, recording position and attributes on the magnetic tape, etc. It is characterized by locating the head at the beginning. Also, when specifying the positioning position, the regularity of the recording / playback processing request (for example, processing within a data set group grouped by arbitrary attributes) and the tape usage method (for example, used sequentially like a conventional tape) It is characterized by specifying whether to use it for backup or to use the data on the tape at random). For example, in the case of the sequential mode, the position of the head is kept at the position after the end of the previous recording / reproducing process, and in the case of the random mode, the head is positioned at a predesignated position on the magnetic tape. Also, when the tape is loaded, the directory information on the magnetic tape is temporarily read into the memory outside the magnetic tape device, and when the directory information is updated, the directory information in that memory is updated, and then when the tape is unloaded, the The feature is that the directory information is recorded again on the magnetic tape.

[0005]

In the present invention, the head positioning position designating unit designates whether or not the head should be positioned at a specific location for each data set search. For example, as a method of using the tape, when all data is backed up, it is not necessary to specify the positioning because the data is overwritten from the beginning of the tape. If a request to play or record data on the same tape is received randomly, specify that the head should be positioned in the middle of the tape, and if the head positioning unit positions it, the data requested to be recorded or played next The average positioning time of the head to the set is reduced. Further, when there is a request for reproduction / recording processing of data in the tape, if there is regularity, by specifying it, the average head positioning time to the data set can be shortened. For example, if the data sets are grouped, and if there are random playback / recording requests within them, the heads can be positioned by specifying the group and the middle position of the group and positioning the heads. Can be shortened. However, when the requests are continuous, it is quicker to position the head directly on the data set to which the next reproduction / recording processing request comes, rather than positioning the head at the designated position one by one. If the tape does not need to be rewound during unloading, the unloading head positioning unit positions it at the location where the directory information indicating the recording position of the data set on the magnetic tape is recorded and unloads it. Then, the next time you use it, immediately
Since the directory information can be read, the positioning time to the dataset can be shortened. In this way, by designating the head positioning position and giving the tape usage method as information, the head positioning preparation can be made in advance.
As a result, the maximum time required for positioning the head is reduced, and the average positioning time can be shortened. Further, when the tape is loaded, the directory information on the magnetic tape is temporarily read into the memory, the directory information is updated, and when the tape is unloaded, the directory information is recorded again on the magnetic tape, so that the update processing can be efficiently performed. .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing the overall configuration of a magnetic tape device control system according to an embodiment of the present invention. In FIG. 2, 1 is a host computer that issues a request for reproduction or recording processing of data in a magnetic tape, 2 is a magnetic tape control device, 3 is a magnetic tape device, and 4 is a terminal for inputting an instruction from an operator. 5a and 5b are operators, and 6 is a magnetic tape. The magnetic tape control device 2 also includes an access control unit 201, a head positioning position designating unit 202,
Head positioning unit 203, unloading head positioning unit 204, positioning data memory 221, directory information storage memory 222, head position storage memory 22
It consists of three. The access control unit 201 receives a data reproduction / recording request from the host computer 1, and starts processing when the requested tape is mounted on the magnetic tape device 3.

Next, the processing in the tape control apparatus after the reproduction / recording request arrives will be described with reference to FIG. Figure 1
3 is a flowchart showing an outline of a magnetic tape device control method according to an embodiment of the present invention. Step 2001: The operator 5b mounts the magnetic tape 6 on the magnetic tape device 3. At this time, the head position storage memory 223 stores the current head position indicating how much data amount (for example, the tape length) is from the head of the tape. As a method of recognizing the head position, a method of detecting an identifier indicating the tape length from the head of the tape, a method of utilizing the thickness of the magnetic tape wound on a reel, or the like can be considered. Hereinafter, every time the head is moved, the information in this memory is updated. For example, when the head positioning position is “middle” and positioning is performed on an arbitrary data set, the head position storage memory 223 is set to the position shown in FIG.
, The directory information position (tape length from the beginning) 2231, the middle position (tape length from the beginning) 22
32, and the current head position (data set number, tape length from the middle) 2233. Step 2002: The access control unit 201 searches recorded directory information such as position information of data in the mounted magnetic tape and stores it in the directory information storage memory 222. In addition, the head position storage memory 2
In 23, the tape length from the beginning is stored as the directory information position.

Here, FIG. 4 shows an example of the directory information, and FIG. 5 shows an example of the directory information storage memory 222. As shown in FIG. 4, in the magnetic tape 6, management information 61 managed on the drive side, information (directory information) 62 regarding a data set recorded on the magnetic tape, and data sets 63 and 64 are recorded. ing. The management information 61 includes a tape identification number 611, a recording format 612, and a tape usage amount 613. Further, the directory information 62 is the information of the data set 63 and after recorded on the tape, and is the file information 62.
1 and tape free area information 622. Further, the file information 621 includes a file (dataset) identification number 6211, a file name 6212, and a data recording capacity 62.
14, the data recording position 6215 is recorded for each data set. It should be noted that the directory information 62 may be anywhere on the tape, and may be in any number. Furthermore, an identifier for recognizing the head position may be set at predetermined intervals. As shown in FIG. 5, the directory information storage memory 222 includes a directory information storage unit 2221 that stores the directory information copied from the tape and a directory information update count storage unit 2222 that stores the number of times the directory information has been updated. The directory information update count storage unit 2222 sets an initial value of 0 and increments by 1 for each update.

Step 2003: Access control unit 201
Gives an instruction to the head positioning position designating section 202 to designate the head position, and the operator 5a selects, for example, the random mode or the sequential mode from the terminal 4
Direct through. The instruction content is stored in the positioning data memory 221. Step 2004: The access control unit 201 positions the head on the data set requested by the host computer 1. At that time, the current head position 2233 of the head position storage memory 223 is updated from the directory information and the current position information obtained in steps 2001 and 2002. Step 2005: The access control unit 201 performs reproduction or recording processing on the data set located in step 2004. At that time, when the directory information is updated, the directory information storage memory 222 is updated. Step 2006: If the reproduction / recording request for the data set in the same tape has already been received from the host computer 1, the process returns to step 2004, and if there is no request yet, the process proceeds to step 2007. By doing so, when there are continuous requests, it is possible to perform the reproducing / recording processing by directly positioning the head on the target data set without once positioning the head at the designated position.

Step 2007: Access control unit 201
When instructed by, the head positioning unit 203 refers to the positioning data memory 221 and the directory information storage memory 222 to position the head at a designated position (for example, the middle).
Position. Step 2008: When a request for a data set in the same tape arrives, the process returns to Step 2004, and if the tape is to be demounted (unloaded), Step 200
Proceed to 9. Step 2009: The access control unit 201 records the directory information in the memory 222 on the tape. Step 2010: Head positioning unit 20 during unloading
By 4, the head is positioned at the location where the directory information is recorded. If there is a plurality of directory information, the latest directory information is selected. Step 2011: The operator 5b demounts the magnetic tape 6 on the magnetic tape device 3. In this way, by giving information on how to use the tape in advance, when the head is next positioned, it is possible to prepare for quick positioning. Further, when the position where the head is positioned is different for each tape, it can be variably designated.

Next, referring to FIG. 6, step 200 of FIG.
3 will be described in detail. FIG. 6 is a flow chart showing the head positioning position designation processing in one embodiment of the present invention. Step 5001: The operator 5a uses the head positioning position designating unit 202 via the terminal 4 in accordance with the guidance on the screen to use the tape using mode (for example, random /
Specify the sequential mode). At this time, indicate the usage pattern of the tape, such as whether to use several data sets recorded on the same tape, or whether to unload the tape after using it once such as backup. To do. Step 5002: If the mounted same tape is used many times, proceed to Step 5003. If it is used only once, proceed to Step 5004. Step 5003: The operator 5a gives an instruction of "head positioning designation (= 1)". In the case of randomly reproducing / recording a plurality of data sets, random (= R) is designated. Further, if the order of regular use is known in advance, the order is designated. Step 5004: The operator 5a inputs "no head positioning designation (= -1)", and proceeds to step 5007. Step 5005: A plurality of data sets are grouped in advance by a certain attribute, and in the group,
If you want to play / record the data set randomly,
The process proceeds to step 5006, otherwise proceeds to step 5007. This group may be set in advance by the operator 5a from the terminal 4 and can be changed at any time, or may be fixedly set, for example, during system configuration. Step 5006: The operator 5a inputs a number or name for identifying a data set belonging to the target group. Also, when requesting playback / recording processing with a command, the user side specifies the data set number and data set name.

Step 5007: The head positioning position designating unit 202 transfers the input contents to the positioning data memory 22.
Store in 1. This memory 221 is as shown in FIG. The positioning data memory 221 of the present embodiment is shown in FIG.
As shown in, the presence / absence information 2211 of the position designation, the group number 2 when the data sets on the tape are grouped
212 and positioning 2213 are stored. This presence information 2
In the field 211, "1" is entered if specified, and "0" is entered if not specified. In the group number 2212 column, the group number and the data set number belonging to the group are input. Also, in the positioning 2213 column, "1" is set if the positioning position is arbitrary, and "2" is set if there is a group.
Are entered, and if the processing order is decided, the order rule is entered with the data set number. When there is a group, the group number and “1” are input if the number is arbitrary in the group, and the order of the data set number is input if the numbers are in order.

Next, referring to FIG. 8, step 200 in FIG.
The process 4 will be described in detail. FIG. 8 is a flowchart showing the data set search processing in the embodiment of the present invention. Step 1301: The head positioning unit 203 calculates the data amount (for example, tape length) from the current head position to the search data set from the current head position in the head position storage memory 223 and the directory information in the directory information storage memory 222. . Step 1302: The head positioning unit 203 calculates the tape feed time to the search data set based on the tape length and the tape feed speed calculated in step 1301. Tape feed time to search data set = tape length / tape feed speed (Equation 1) Step 1303: The access control unit 201 sends the tape for the time calculated in Step 1302. Step 1304: The access control unit 201 performs a positioning process for positioning the search data set position. Step 1305: If the previous head position is not in the middle, proceed to step 1306. If the previous head position is in the middle, proceed to step 1307. Step 1306: The head positioning unit 203 calculates the tape length from the center position of the head to the current head position,
It is stored in the memory 223. Step 1307: The head positioning unit 203 stores the tape length of Step 1302 in the memory 223.

Next, referring to FIG. 9, step 200 in FIG.
The process 5 will be described in detail. FIG. 9 is a flow chart showing a data reproducing / recording process in the embodiment of the present invention. Step 6001: The access control unit 201 performs update or reproduction processing on the data set searched in step 2004. In the case of update processing, step 600
2, the process proceeds to step 6003 in the case of reproduction processing. Step 6002: The access control unit 201 performs a process of updating data, and proceeds to step 6004. Step 6003: The access control unit 201 performs a process of reproducing data, and ends the process of this step 2005. Step 6004: The access control unit 201 updates the directory information in the directory information storage unit 2221 in the directory information storage memory 222, if necessary. Step 6005: When the directory information is updated in step 6004, the access control unit 201 increments the contents of the directory information update count storage unit 222 by 1.

Next, referring to FIG. 10, step 20 in FIG.
The processing of 07 will be described in detail. FIG. 10 is a flowchart showing the head positioning process in the embodiment of the present invention. In this embodiment, the head is positioned in the middle in order to position it on an arbitrary data set. Step 7001: The access control unit 201 issues a positioning instruction to the head positioning unit 203 according to the designation made by the operator 5a from the terminal 4 in advance. Step 7002: The head positioning unit 203 refers to the positioning designation information from the positioning data memory 221. Step 7003: The head positioning unit 203 proceeds to Step 7004 when the positioning of the information in the memory 221 is designated, and this Step 200 when not designated.
The process of 7 is completed. Step 7004: The head positioning unit 203 proceeds to step 7005 if the current head position has not been searched for the data set after tape mounting, otherwise proceeds to step 7006. As a method for recognizing the head position, for example, a method based on the tape length, a method using identifiers arranged at predetermined intervals on the tape, etc. are generally known, and the head position is recognized by this method also in this embodiment. . Step 7005: The head positioning unit 203 searches for the head of the data set from the middle, out of the data sets in the middle from the head of the tape recording area. It should be noted that, regardless of the present embodiment, the positioning of the head is, for example, one of the tape length.
Any position such as the position of / 2 may be set. Step 7006: The head positioning unit 203 calculates the tape feed time from the current head position information 2233, and proceeds to step 7008. Step 7007: The head positioning unit 203 calculates the data amount (for example, tape length) up to the search position of the data set of Step 7006, and calculates the tape feed time. Tape feeding time = tape length / tape speed (Equation 2) Step 7008: The head positioning unit 203 performs the tape positioning operation as in Step 2004. Step 7009: The access control unit 201 stores the current head position in the head position storage memory 223.

Next, referring to FIG. 11, step 20 in FIG.
The processing of 09 will be described in detail. FIG. 11 is a flow chart showing the head directory update processing in the embodiment of the present invention. Step 8001: The access control unit 201 proceeds to step 8002 if the number of updates of the directory information storage memory 222 is 1 or more, that is, if there is an update, otherwise ends the processing of step 2009. Step 8002: The access control unit 201 positions the head to the position where the directory information is recorded. Step 8003: The access control unit 201 uses the memory 2
Record the latest directory information from 22 on the tape. As a result, the directory information in the magnetic tape can be updated efficiently.

FIG. 12 shows the operation of positioning the head in the tape. In this embodiment, the magnetic tape 6 has a data storage area 60 including directory information 62, a data set 63 and the like. For example, when the tape is used only once such as backup, the head operates from head position a to head position d to head position a.
Further, when processing is performed on an arbitrary plurality of data sets, the head operates as head position a to head position b to head position (for example, the middle position) c to ... to head position a. However, if the requests are continuous, the positioning of the head is omitted. FIG. 13 shows the head positioning operation in the case shown in FIG. 6 (when data sets are grouped). This is an example of arbitrary positioning within the group A. If the data set 64 is requested first, the head position a to the head position (for example, the middle position of the group A) b to the head position c (next Request data set position) ...

[0018]

According to the present invention, when a data set recorded on the same tape is required to be repeatedly processed, the maximum value of head movement is reduced by giving information on how to use the tape in advance. be able to. Further, when the requests are continuously made, the head is not positioned at the designated position but directly positioned at the data set, so that the average positioning time can be shortened. In addition, by storing the directory information necessary for positioning the data set in the memory when the tape is loaded, the head does not have to be positioned in the directory information each time a request is made. Also, the directory information in the magnetic tape can be updated efficiently. Also, since it is necessary to read the directory information immediately after tape loading, when unloading, if the directory information is positioned, the directory information can be read immediately after loading.

[Brief description of drawings]

FIG. 1 is a flowchart showing an outline of a magnetic tape device control method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a magnetic tape device control system according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a head position storage memory according to an embodiment of the present invention.

FIG. 4 is a diagram showing a structure of directory information according to an embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a directory information storage memory according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a head positioning position designation process in an embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a positioning data memory according to an embodiment of the present invention.

FIG. 8 is a flowchart showing a data set search process according to an embodiment of the present invention.

FIG. 9 is a flowchart showing a data reproducing / recording process in an embodiment of the present invention.

FIG. 10 is a flowchart showing a head positioning process in an embodiment of the present invention.

FIG. 11 is a flowchart showing a head directory update process according to an embodiment of the present invention.

FIG. 12 is a diagram showing a head positioning operation in one embodiment of the present invention.

FIG. 13 is a diagram showing a head positioning operation when grouping is performed in an embodiment of the present invention.

[Explanation of symbols]

 1 host computer 2 magnetic tape control device 3 magnetic tape device 4 terminal 5a operator 5b operator 6 magnetic tape 201 access control unit 202 head positioning position designation unit 203 head positioning unit 204 unloading head positioning unit 221 positioning data memory 222 directory Information storage memory 223 Head position storage memory

Claims (10)

[Claims] 1. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, wherein when the next data set to be reproduced / recorded is undecided, the head is magnetically moved. A method for controlling a magnetic tape device, characterized by locating the tape at a predetermined position on the tape. 2. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape on which a plurality of data sets are recorded, wherein a half of the total recording capacity of the data sets on the magnetic tape or the magnetic tape length. A magnetic tape device control method characterized in that the head is positioned at a position corresponding to any one of the two, and reproduction / recording is performed on an arbitrary data set. 3. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, wherein the head positioning position is half the total recording capacity of the data set in advance. Or at a position corresponding to one half of the length of the magnetic tape, and the data set to be reproduced / recorded next is undecided, the data set closest to the specified position from the beginning of the tape storage area Search the head of the device, calculate the tape feed time from the tape speed of the device to the specified position and perform positioning operation, and update the directory information obtained from the magnetic tape when the tape is mounted and the current head position information. After the registration and subsequent reproduction / recording processing, the tape feed time to the specified position is calculated based on the head position information, and the positioning operation is performed. A method for controlling a magnetic tape device, comprising: 4. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded thereon, wherein the data sets recorded on the magnetic tape are divided into a plurality of groups in advance, A method for controlling a magnetic tape device, wherein when reproducing / recording a data set of a specified group, the head is positioned at a predetermined position on the magnetic tape. 5. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded thereon, wherein the data sets recorded on the magnetic tape are divided into a plurality of groups in advance, When performing reproduction / recording on the data set in the specified group, it is set at a position corresponding to either one half of the total recording capacity of the data set of the group or one half of the magnetic tape length in the group. A method for controlling a magnetic tape device, which comprises positioning a head. 6. A method for controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded therein, wherein the data sets recorded on the magnetic tape are grouped into a plurality of groups according to preset attributes. When the tape is mounted, the directory information on the magnetic tape is read, the tape use mode indicating random playback / recording, and the identification information including the group number are specified and input. A magnetic recording medium characterized by performing reproduction / recording on a set and positioning the head at a position corresponding to either one half of the total recording capacity of the data set of the group or one half of the length of the magnetic tape in the group. Tape device control method. 7. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, wherein when the next data set to be reproduced / recorded is undecided, the head is magnetically recorded. If the next playback / recording request has already arrived at the time when the playback / recording processing for the data set on the magnetic tape is completed by positioning it at a predetermined position on the tape and following the playback / recording request. A method for controlling a magnetic tape device, characterized in that the head is directly positioned on the created data set. 8. A method for controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, and when reproducing / recording sequentially, the position of the head is recorded / reproduced last time. A method for controlling a magnetic tape device, wherein the head is positioned at a predetermined position on the magnetic tape when the reproduction / recording is performed randomly while keeping the position after the end. 9. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, wherein when the next data set to be reproduced / recorded is undecided, the head is magnetically recorded. When the tape is positioned at a predetermined position on the tape and can be unloaded without rewinding to the beginning of the magnetic tape, it is recorded on the tape when it is unloaded from the magnetic tape device. A method for controlling a magnetic tape device, characterized in that the head is positioned at the beginning of the existing directory information. 10. A method of controlling a magnetic tape device for positioning and reproducing / recording a head on a magnetic tape having a plurality of data sets recorded, wherein a directory recorded on the tape when the magnetic tape is loaded into the device. When the information is read into the memory outside the device and the directory information is updated in accordance with the reproduction / recording processing of the data set in the tape, the directory information read in the memory is updated, and when the tape is unloaded, the memory is updated. A method for controlling a magnetic tape device, characterized by re-recording the latest directory information in the magnetic tape.