JPH04104315A - File retrieval system for magnetic tape device - Google Patents

Abstract

PURPOSE:To position a tape up to a file to be retrieved at rewinding speed at the time of file retrieval by permitting a magnetic tape retrieval sensor to detect the position of the file on the tape. CONSTITUTION:Writing into the tape is executed from a program, a tape position in the head of the file is detected and data is written into VTOC. When the writing into the tape is terminated, the tape position at the end of the file is detected and data is written into VTOC. When the name of the file 'FFF' is read by the program, VTOC is retrieved first, and the start position of the tape is detected. The magnetic tape is fast forwarded to the immediate front of the tape start position '104'. HDR of 'FFF' is searched from the position and 'FFF' is retrieved. When th unload instruction of the tape is executed, VTOC on the memory is written into the VTOC area of the magnetic tape and the tape is unloaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the use and operation of a magnetic tape device, and particularly to a file search method when a plurality of files are stored on one volume of magnetic tape.

[Conventional technology]

File searches in conventional magnetic tape devices have been carried out by searching for HDR (file header) from the beginning of the magnetic tape by specifying a file sequential number or an external file name, and locating the file to be searched.

[Invention or problem to be solved]

The conventional file search method described above is based on HD files on magnetic tape.
The method is to search for R and locate the file you want to search, so if multiple files are stored on one magnetic tape, if you try to search for a file at the back of the magnetic tape, the search will start from the beginning of the magnetic tape. HDR is searched until the desired file is found. in this case,
Since the contents of the HDH are searched as fast as it can be read, the disadvantage is that it takes a very long time to search for a file.

[Means to solve the problem]

The file search method of the magnetic tape device of the present invention has a magnetic tape position search sensor, and the sensor expresses numerically where a file starts and ends on the magnetic tape, and the numerical value is stored in the file. This is realized by storing the magnetic tape in the VTOC area as a position, and during file search processing, reading the VTOC area, detecting the file storage position, and then positioning the magnetic tape.

〔Example〕

FIG. 1 is an explanatory diagram of a file structure of a magnetic tape showing an embodiment of the present invention. In the figure, the first file ]a is the VTOC.

FIG. 2 is an explanatory diagram showing an example of a magnetic tape device that implements the present invention. In the figure, a magnetic tape device 10 is a magnetic tape remaining amount position search sensor 1 that detects the position of the tape.]
has.

FIG. 3 is an explanatory diagram showing the operation of mounting the magnetic tape 1 on the magnetic tape device 10. When the magnetic tape is mounted, the VTOC of the magnetic tape is read simultaneously with BOT detection and loaded into the memory of the magnetic tape device control section.

FIGS. 4(a) to 4(f) are explanatory diagrams showing the operation of writing and retrieving files on a magnetic tape by a program.

In FIG. 4(a), a portion A is detected by the magnetic tape remaining amount position search sensor, and the position of the end of the tape is converted into a numerical value. The converted value is VTOC
is stored in the tape position information.

In FIG. 4(b), when the program writes to the tape, the tape position of the head of the file is first detected and written to the VTOC.

In FIG. 4(c), when writing to the tape is completed, the tape position at the end of the file is detected and written to the VTOC. Assume that by repeating the above operations, the VTOC information becomes as shown in FIG. 4(d).

In FIG. 4(e), when the program reads the file name "FFF", the VTOC is first searched and the tape start position is detected.Then, the magnetic tape position is just before the tape start position "104". Fast-forward the magnetic tape to the point. From that position, search for the HDR of "FFF" and search for the file "FFF". FIG. 4(f) is an explanatory diagram showing the above situation.

When a tape TJ NL OA D command is executed, the VTOC on the memory is written to the VTOC area of the magnetic tape, and the tape is UNLOADed. This magnetic tape device is also compatible with the ability to read and write magnetic tapes created with conventional magnetic tape devices (first
It depends on whether the file is a VTOC or not. ),
Traditional resources are also available. Furthermore, when a file created by this magnetic tape device is used in a conventional magnetic tape device, the first file (VTOC) can be used without skipping.

〔Effect of the invention〕

As explained above, the present invention uses a magnetic tape search sensor to detect the position of a file on a tape, and when searching for a file, it is possible to locate the file to be searched at the speed of rewinding, thereby significantly improving search speed. can be done. Therefore, there is an effect of improving the usage image of the magnetic tape device, which has been complicated up to now.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a magnetic tape file structure according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of a magnetic tape device, and FIG. 3 is an explanatory diagram showing a magnetic tape mounting operation. , FIGS. 4(a) to 4(f) are explanatory diagrams showing the operation. 1... Magnetic tape, 1a... First file (VTOC)
), 10... Magnetic tape device, 1]... Magnetic tape remaining amount position search sensor

Claims (1)

[Claims] It has a magnetic tape position search sensor, which numerically represents where a file starts and ends on the magnetic tape, stores the numerical value in the VTOC area as a file storage position, and when performing file search processing, the A file search method for a magnetic tape device, characterized in that the magnetic tape is positioned by reading a VTOC area and detecting the file storage position.