JPH04293116A - Tape system storage device control method - Google Patents

Abstract

PURPOSE:To enable the head movement to the leading position of a designated file in the shortest time by recognizing the leading position of a current on a tape, and the leading position of the designated file in a control method of a tape system storage device for controlling an access to the tape system storage device inputted/outputted by a block unit. CONSTITUTION:In the final part of information stored in a tape, retrieval information 18 related to the start block position of each file on the tape is recorded, and at the time of setting the tape, this retrieval information 18 is inputted. At the time of making an access to files 17a-17c, the head movement to the leading position of the file is carried out from the leading position of the current, and start block position information of the file obtained from the inputted retrieval information 18.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention enables efficient access to tape-based storage devices such as magnetic tapes and cartridge magnetic tapes (hereinafter referred to as CRMT) used as storage media for sequential files. This invention relates to a tape storage device control method.

[0002] Tape storage devices are used as storage media for sequential files, sequentially starting from the beginning of the tape. In conventional tape storage devices, when searching for a file stored on a tape, it is necessary to search from the beginning of the tape to the block where the target file is located. If there was a way to directly point to the beginning of a specified file, it would be possible to shorten the read time.

0003

2. Description of the Related Art FIG. 8 shows a tape file structure in a conventional CRMT device. The format of a file in a conventional CRMT device is such that data is stored in blocks of 512 bytes, as shown in FIG. 8, for example. In Figure 8, BOT is the tape start mark, BL
1 to BL7 are blocks in which file contents are stored, F
M represents a file mark indicating the end of the file. If the file is the last file on the tape, two consecutive file marks FM are recorded at the end.

[0004] When accessing a tape in this format, in the conventional technology, when searching for a file, the search is performed from the position of the tape start mark BOT, and the block following the file mark FM is recognized as the beginning of the file. I was searching for files. If the found file is not the target file, the next file is searched in the same way, and the search is repeated until the target file is found or two consecutive file marks FM are found.

[0005]

[Problem to be Solved by the Invention] Therefore, in the conventional method, in order to find the specified file, one rewinds the tape (rewinds the tape), returns the current head position to the beginning of the tape, and then It was necessary to perform file search operations.

The present invention aims to solve the above problems and moves the head to the beginning of the specified file in the shortest possible time by recognizing the current head position on the tape and the starting position of the specified file. The aim is to make it possible.

[0007]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, 10 is a data processing device including a CPU and memory, 11 is an application program that processes data on files stored on a tape storage medium, and 12 is an operating system that provides system service functions for the application program 11. 13 is a tape input/output control unit that controls input/output to a tape storage medium; 14 is a search information buffer in memory that stores search information; 15 is a tape such as a magnetic tape device or a cartridge magnetic tape (CRMT) device; System storage device, 1
6 is a tape storage medium, 17a to 17c are files, 18
represents search information having starting block position information for each file.

The tape input/output control unit 13 records search information 18 regarding the starting block position of each file on the tape in the last part of all files stored in the tape storage medium 16. When setting the tape, this search information 18 is taken into the search information buffer 14. When accessing files 17a to 17c, the target file start position is accessed from the current head position and the file start block position information obtained from the search information 18 imported into the search information buffer 14. Move the head.

That is, the head position of the tape storage device 15 is recognized during tape operation, and the file name and head position are memorized in the search information buffer 14 during write processing in response to a request from the application program 11. When all processing on the tape storage medium 16 is completed, the files 17a to 17 modified by the operations at that time are
All start block position information of c is written from the search information buffer 14 onto the tape storage medium 16 as search information 18. When removing the tape, remove it without rewinding it.

[0010] After that, when accessing the tape storage medium 16, go back one file when setting the tape, and
The information is read out and set in the search information buffer 14. After confirming that the information set in the search information buffer 14 is the search information 18, calculate the current head position and the head position of the target file, and skip the number of blocks that are the difference between them to find the target file. Point to a file.

[0011]

According to the present invention, the search information 18 is recorded at the end of the tape storage medium 16, and the starting block position (storage block number) of each file 17a to 17c is set therein. The information is read when the tape is opened, and the storage block number of the specified file is extracted from the search information 18. This allows you to compare the currently pointed block number and the retrieved block number,
Move the tape by that difference. By doing this, when pointing to the next file, it is possible to point to the desired position with the minimum amount of movement from the current position.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a diagram showing a file structure of a tape according to an embodiment of the present invention, and FIG. 3 is a diagram showing a data structure of search information according to an embodiment of the present invention. The tape has 512
Data is recorded sequentially in blocks, with a byte as one block. In FIG. 2, BOT represents a tape start mark, BL1 to BL7 represent blocks in which file contents are stored, and FM represents a file mark indicating the end of a file.

In the example of FIG. 2, file a has 4 blocks,
File b consists of two blocks. In this embodiment, after this final file b, search information 1 is added.
8 is stored. This search information 18 formally has a structure of one file. Therefore, search information 18
Two file marks FM are successively recorded after .

The data structure of the search information 18 is shown in FIG. 3, for example.
It has information that associates the storage file name of each file with the starting point position where that file is stored. Regarding the search information 18, information on the leading point position is also set. In addition, as part of the search information 18, the search information identifier or the search information 18
It may also have size information, etc.

FIG. 4 is a flowchart at the beginning of a tape operation according to an embodiment of the present invention. ■ In the following explanation
~■ correspond to processes ■~■ shown in FIG. (2) When power is turned on or a tape is loaded into the tape storage device 15 shown in FIG. 1, the tape position is first moved forward by one file.

(2) At this time, if the tape position is at the beginning of the tape, the process proceeds to process (2), and if it is not at the beginning of the tape, the process proceeds to process (2). (2) If the tape position is not at the beginning of the tape, the contents of the tape are read from that position and stored in the search information buffer 14 in memory. This information is search information 18, but if it is not search information 18, the tape is rewound and the same tape control as in the prior art is performed.

■ Since the search information 18 read into the search information buffer 14 contains information on the leading point position on the tape where the search information 18 is stored, the current position is determined from that information and the current position is determined at the time of access. The tapepointer used for block skipping control is
Store it as the current point position and end the process.

(2) If the tape position is at the beginning of the tape, it is recognized that the tape is a new tape or a tape created by a conventional method. Therefore, the search information buffer 14 is initialized to a state of "no search information". ■ Set the tape pointer to 0 and end the process.

FIG. 5 shows a tape re according to an embodiment of the present invention.
It is a flowchart at the time of ad. ■ In the following explanation
~■ correspond to processes ■~■ shown in FIG. ■ Since the current position of the tape and the search information 18 have been prepared in the process at the start shown in Figure 4, the search information 18 on the search information buffer 14 is checked from the file name specified for reading. Find the starting point position of the file.

(2) Compare the obtained leading point position with the current position, and if the leading point position is larger, proceed to process (2). If the first point position is small, proceed to process (■). ■ Skip forward the number of blocks equal to the current position minus the first point position of the specified file, and proceed to process ■.

■ Calculate the number of blocks by subtracting the current position from the starting point position of the specified file.
Read backwards. ■ Process ■ or process ■ positions the head at the first block of the specified file. Therefore, t
Set ape pointer to the current point position.

[0022] Data is read from the tape pointer position. (2) When reading data, the number of blocks read is stored, and after reading, the number of blocks read is added to the tape pointer. FIG. 6 is a flowchart when writing a tape according to an embodiment of the present invention. ■ to ■ in the following description correspond to processes ■ to ■ shown in FIG.

■ At the time of write, the current position of the tape and the search information 18 are prepared as in the case of read, so the current point position and each leading point position in the search information 18 are compared, It is checked whether the current point position is registered in the search information 18. If the tape is new, there is no corresponding starting point position information, so the next process (2) is skipped.

■ If the same value as the current point position at which writing starts is in the head point position information in the search information 18, new data will be written after that position, so the search after that position will be performed. Delete all information in information 18. This is because in the tape storage device 15, the contents of data after the block in which the data was written become invalid. Note that this embodiment assumes that data will not be written from the middle of an existing file.

(1) Write the specified file name and the current point position at which data writing starts to the final position of the search information 18 in the search information buffer 14. ■ Write specified data. (2) After writing the data, add the number of blocks to be written to the tape pointer, point to the current position after writing, and end.

FIG. 7 shows a close diagram according to an embodiment of the present invention.
It is a flowchart of the time. ■～■ in the following explanation
corresponds to processes ① to ② shown in FIG. ■ Whether data was written between opening and closing, that is, search information 18
Determine whether there has been any rewriting. If no data has been written, proceed to process ■.

(2) When data is written, the current block position on the tape is adjusted to the final position of the data. ■ The file name of the search information 18 itself and the current block position are stored in the search information 18 in the search information buffer 14.
recorded at the end of

(2) The contents of the search information buffer 14 are written after the last data on the tape, and the process is terminated. ■ If no data has been written, points to the last position of data on the tape and ends.

In this embodiment, the tape is normally not rewound after the tape operation is completed. If there is no need to replace the tape storage medium, the service may be terminated by turning off the power with the tape still attached to the drive.

[0030]

[Effect of the invention] As explained above, according to the present invention,
To access any file on a tape storage medium, there is no need to search from the beginning of the tape, and it can be accessed from the current position with the shortest head movement, significantly reducing file search time. can do.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram showing a file structure of a tape according to an embodiment of the present invention.

FIG. 3 is a diagram showing a data structure of search information according to an embodiment of the present invention.

FIG. 4 is a flowchart at the beginning of a tape operation according to an embodiment of the present invention.

FIG. 5 is a flowchart when reading a tape according to an embodiment of the present invention.

FIG. 6 is a flowchart when writing a tape according to an embodiment of the present invention.

FIG. 7 is a flowchart at close according to an embodiment of the present invention.

FIG. 8 is a diagram showing a file structure of a conventional tape.

[Explanation of symbols]

10 Data processing device 11 Application program 12 Operating system 13
Tape input/output control unit 14 Search information buffer 15 Tape storage device 16 Tape storage media 17a to 17c File 18 Search information

Claims (1)

[Claims] Claim 1. In a tape storage device control method for controlling access to a tape storage device (15) that performs input/output in blocks, the final part of the information stored on the tape includes information about each file on the tape. Record the search information (18) regarding the starting block position, import this search information (18) when setting the tape, and save the file (17).
a to 17c), the head is moved to the beginning position of the file based on the current head position and the starting block position information of the file obtained from the retrieved search information (18). A tape storage device control method.