JPH02161657A - Method for managing storage of magnetic tape device - Google Patents

Abstract

PURPOSE:To shorten file access time by calculating the number of times of access and the frequency of access of respective file, duplicating the file whose number of times of access or frequency of access exceeds a normal value on the unused area of a magnetic tape, and making access to duplicated file data hereafter. CONSTITUTION:The present date information is obtained from a clock circuit 4, and the number of days elapsed from the registration day of targeted index data is calculated, and the access frequency is calculated by dividing the number of times of access by the number of days elapsed, and it is checked whether or not the access frequency exceeds a constant value. And the file whose number of times of access or frequency of access exceeds the normal value is duplicated on the unused area of the magnetic tape, and the duplicated file data is made accessed hereafter. Therefore, a tape feed time can be shortened since the file with high access frequency is concentrated on the specific storage area of the magnetic tape. In such a manner, it is possible to shorten the file access time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a storage management method for a magnetic tape device that stores a plurality of files on a magnetic tape in the order in which they were recorded.

[Prior Art] A magnetic tape device that uses magnetic tape as a storage medium is
For example, it is used in a data processing device that registers/reproduces image data.

In such a magnetic tape device, file data is stored on the magnetic tape in the order of storage occurrence, and in order to efficiently access the stored files,
An index file is formed that includes identification information and storage area information for each file. This index file is stored, for example, in the first storage area of the magnetic tape.

When accessing a file stored on a magnetic tape, first read the index file, obtain storage area information for the file to be accessed based on its contents, and access the target file based on that storage area information. ing.

[Problems to be Solved by the Invention] However, in such a conventional device, file access is performed relatively frequently over the front area of the magnetic tape, resulting in a disadvantage that the file access time becomes long.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a storage management method for a magnetic tape device that can eliminate such disadvantages of conventional devices and shorten file access time.

[Means for Solving the Problems] The present invention provides means for calculating the number of accesses and access frequency of each file, and for files whose access number or access frequency exceeds a specified value, the unused area of the magnetic tape is After that, the copied file data is accessed.

[Effects] Therefore, since files that are accessed particularly frequently are concentrated in a specific storage area of the magnetic tape, the tape running time is shortened, and as a result, the file access time is shortened.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a data filing system using a magnetic tape device as a data file means according to an embodiment of the present invention.

In the figure, a CPU (Central Processing Unit) 1 is for controlling the data filing system, and a ROM (Read Only Memory) 2 is for controlling the CPU.
It stores the processing program executed by I and various data required when executing the processing program.
M (random access memory) 3 constitutes a work area of the CPUI, and a clock circuit 4 is for obtaining current time and date information.

The keyboard device 5 is used by the operator to input commands for operating the data filing system, and the CRT device 6 is used to display and output various display information from the data filing system to the operator. The magnetic tape device 7 is for storing/reproducing a large number of file data.

These keyboard device 5, CRT device 6, and magnetic disk device 7 are connected to interface circuits 8 and 7, respectively.
CP via 9.10? , J 1 system bus 1
Connected to 1.

Further, the keyboard device 5 and the CRT device 6 are
The control action of the I allows for communication between the operator and the system.
Configure machine interfaces.

An example of a magnetic tape storage format in the magnetic tape device 7 is shown in FIG.

On the magnetic tape, a large number of blocks 8L each consisting of a data string of a certain length are arranged with a gap GP of a certain length in between, and each block BL is arranged in a manner similar to that of each block 81 . Block address All for identifying
, and block data BD of a certain length.

The file data is divided into lengths of block data 8D and stored in continuous block areas of the magnetic tape.

In order to efficiently access file data stored on magnetic tape, for example, an index file as shown in FIG. 3 is created.

This index file contains, for each file data, a file number FN for identifying each file data, a file name NM given to each file data, attribute information AT such as the creator and date and time of creation, and magnetic tape. Registered date D
T, the number of accesses TN, which indicates the number of accesses, the first block address TA, which indicates the first block of the area where file data is stored, and the number of used blocks HA, which indicates the number of blocks occupied by the file data. Index data is stored.

Further, the access count TN is initially set to O when new file data is registered.

FIG. 4 shows a mask pointer in which the usage status of the magnetic tape is registered.

This mask pointer includes an unused area pointer PB that indicates the block address AB of the first block of the unused area of the magnetic tape set in the magnetic tape device 7;
It consists of an index file pointer PI that indicates the block address 8B of the block opening L where the index file is stored, and the first block B of the magnetic tape.
L, that is, block address AB is stored in block BL of [0000].

With the above configuration, when a new magnetic tape is installed in the magnetic tape device 7, the CPU first stores a mask pointer in the first block BL of the storage area of the magnetic tape, as shown in FIG. 5(a). , stores the index file in the next block BL, and stores the master pointer generated at that time in the RAM3.

At this time, the index data of only the index file is registered in the index file. In addition, the block address AB of the next block 8L in the storage area of the index file is stored in the unused area pointer PB of the master pointer.
Block 131.I stores an index file. block addresses AB are registered respectively.

From now on, each time an operator requests registration of a data file, that data file is registered in the magnetic tape device 7, and each time the data file is registered, index data regarding each data file is created and the index file is updated. At the same time, the mask pointer stored in the RAM 3 is updated.

When this data filing system is powered off, or when the magnetic tape stored in the magnetic tape device 7 is replaced, the magnetic tape is stored in accordance with the contents of the master pointer stored in the RAM 3. -Update the contents of the mask pointer stored in -.

For example, the contents of the storage area of the magnetic tape when two data files are registered are as shown in FIG. 5(b). Note that these data files are generated manually from an external device (not shown) or by the CPU executing an application program.

Now, when a data file registered on a magnetic tape is accessed and its contents are displayed on the CRT device 6 or used by other application programs, each time the data file is accessed, the CPU Execute the process shown in Figure 6 to move the data files registered on the magnetic tape.

That is, by referring to the contents of the index file pointer PI of the master pointer stored in the RAM 3, the index file is read from the magnetic tape device 7 (step 102), and based on the contents of the read index file, the magnetic tape device A list of data files stored in the computer 7 is displayed on the CRT device 6 through interactive processing.

The operator is prompted to select a data file to access (process 102).

Thereby, when the operator selects a data file, the CPUI displays the index data (hereinafter referred to as target index data) of the selected data file.
, the selected data file is read (process 103), and the access count TN of the target index data is incremented and updated (process 104).

Next, the current date information is obtained from the clock circuit 4, and the number of days that have passed since the registration date DT of the target index data is calculated.
The access frequency is calculated by dividing the number of accesses TN by the number of elapsed days, and it is checked whether the access frequency is equal to or higher than a certain value A (determination 105).

When the result of judgment 105 is '/ES, obtain the unused area pointer PB of the mask pointer (process 106).
.

The difference between the start block address TA of the target index data and the unused area pointer P8, that is, the distance 1) S from the beginning of the data file accessed at that time to the unused area is calculated (107), and the distance DS is Check whether it is greater than a certain value B (judgment 108)
.

When the result of judgment 108 is Y[', S, the data file accessed at that time is copied to the beginning of the unused area (1O9), and the value of the first block address TA of the target index data is copied to the unused area. To update the value of the pointer PB, the content of the unused area pointer PB is updated to the current value plus the number of used blocks A of the target index data (process 111).

In this way, data files that are accessed frequently and whose distance from the unused area is more than a certain value are copied to the beginning of the unused area, and the contents of the index data related to that data file are copied. , it is updated to indicate the newly copied data file, so from then on, the copied data file will be accessed.

Further, for the index file, the same process shown in FIG. 7 as for the data file is executed.

That is, the number of accesses TN of the index data related to the index file is incremented and updated (step 201), and it is checked whether the access frequency has become equal to or higher than a certain value A (determination 202).

If the result of the judgment 203 is YES, an unused area pointer is obtained (process 203), a distance DS from the index file to the unused area is calculated (process 204), and the distance MDS is greater than or equal to a certain value B -1-, (Judgment 205).

When the result of judgment 205 is YES, the index file is copied to the first block of the unused area (process 206), and the contents of the first block address TA of the index data related to the index file and the two index file pointers of the mask pointer are copied. is updated to the value of the unused area pointer PB (207),
The value of the unused area pointer PB is incremented and updated (processing 208).

In this way, when the access frequency of the index file exceeds a certain value and the distance from the unused area exceeds a certain value, a copy of the index file is created in the unused area, and from then on, , and use the index file obtained by copying it (see FIG. 5(C)).

In general, for data files stored on magnetic tape, there is a tendency for new information to be read out frequently and old information to be read out infrequently.
There is specific information that is frequently accessed regardless of whether it is old or new. There is a rule of thumb:

In this case, the "new information" is registered in the unused area, so if you copy the frequently accessed data file to the unused area and use the copied data file from then on, the new information will be registered. data files that have been accessed frequently, and data files that have been accessed frequently up to that point.
You can concentrate on a somewhat limited area.

In addition, when accessing a data file, "specific information" that is accessed frequently and that is always accessed in advance.
Since index files are also stored in areas close to unused areas, the distance that the magnetic tape travels between accessing the index file and accessing the target data file can be shortened to a certain extent. , the data file access time can be shortened.

Note that the access frequency reference value A and distance DS reference value B that are referenced when moving a data file, and the access frequency reference value A and distance DS reference value B that are referenced when moving an index file are as follows. It can also be set to values that correspond to each of the data file and index file.

By the way, in the above-mentioned embodiment, "the access frequency has exceeded a certain value and the distance from the beginning of the file storage area to the unused area has exceeded a certain value" is determined by the data file or index file. This is a movement condition, but in addition to this movement condition,
The number of accesses becomes less than a certain value, or -), and the distance from the beginning of the file storage area to the unused area becomes more than a certain value. You can use "become no koto".

In that case, each time a file is moved, if you clear the number of accesses for that file to O, you can also
(Updates the content of the child file move date to prepare for the next file move.

In addition, as a file movement condition, it is possible to use the condition that the access frequency or the number of accesses is less than a certain value.

Further, in the embodiment described above, the number of recording tracks set on the magnetic tape is one, but the present invention can be similarly applied to a case where there are two or more recording tracks.

In the above-described embodiment, the mask pointer is composed of the unused area pointer and the index file pointer, but the master pointer may also include index data related to the index file. In that case, it is not necessary to include the index data of the index file itself in the index file.1 Note that the present invention can be similarly applied to a file system that does not create an index file.

Furthermore, the present invention is applicable to systems other than the data loading system shown in FIG. , - can be similarly applied.

[Effects of the Invention] As explained above, according to the present invention, a means is provided for calculating the number of accesses and access frequency of each file, and for files whose access number or access frequency exceeds a specified value, magnetic tape The data is copied to an unused area of the magnetic tape, and the copied file data is accessed from then on, so files that are accessed frequently are concentrated in a specific storage area of the magnetic tape, which reduces the tape running time. As a result, the file access time is shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating a data filing system according to an embodiment of the present invention; FIG. 2 is a schematic diagram illustrating a magnetic tape recording format; FIG. 3 is a schematic diagram illustrating an example of an index file; FIG. 4 is a schematic diagram showing an example of a mask pointer, FIGS. 5(a) to (c) are schematic diagrams showing an example of changes in the storage contents of a magnetic tape, and FIG. 6 is a schematic diagram showing an example of processing when accessing a data file. Flowchart, 7th
The figure is a flowchart showing an example of processing when accessing an index file. ■...CPU (Central Processing Unit), 2...ROM (Read Only Memory), 3...RAM (Random Access Memory). Figure 1 Figure 2 + 31 + Figure Figure Figure (a) Figure (b) Figure (C)

Claims (2)

[Claims] (1) In a storage management method for a magnetic tape device that stores multiple files on a magnetic tape in the order in which they were recorded, a means is provided to calculate the number of accesses and access frequency of each file, and the access number or access frequency is set to a specified value. 1. A storage management method for a magnetic tape device, characterized in that files exceeding the maximum capacity are copied to an unused area of the magnetic tape, and thereafter the copied file data is accessed. (2) In a storage management method for a magnetic tape device that stores multiple files on a magnetic tape in the order in which they were recorded, a means is provided to calculate the number of accesses and access frequency of each file, and the access number or access frequency is set to a specified value. For files whose distance from the unused area of the magnetic tape to the storage area exceeds a certain value, the files are copied to the unused area of the magnetic tape, and from then on,
A storage management method for a magnetic tape device, characterized by accessing the copied file data.