JPH0512080A - Disk media control system - Google Patents

Abstract

PURPOSE:To shorten the retrieving time of the idle area of disk media and to make efficient the use of the data area. CONSTITUTION:A file operation is performed by the control of a directory 2, a file allocation table 3 and a bit map area 5. For the bit map area 5, at the time of the file operation, a bit 1 is written and updated at the time of 'use', and a bit 0 is written and updated at the time of 'unuse'. When the file is prepared by plural continuous clusters, a device driver 6 refers to the bit map area 5 and retrieves the area in which the bit 0 is continuous in which more than the designated number of clusters show the 'unuse'. Out of the retrieved result, with the result having the small difference between the most requested number of clusters and the number of idle clusters as a decided value, the file is prepared at the area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk medium management system, and more particularly to a disk medium management system for managing the usage status of disk media in a table format.

[0002]

2. Description of the Related Art Conventionally, in this type of disk medium management method, a catalog (directory) storing information about files such as file names, file creation dates, and file sizes existing on the disk medium, and the use of file data areas are used. It is managed by a table (file allocation table) that manages the status and the allocation status of the file on the medium and the actual data area.

FIG. 3 is a file configuration diagram of an example of a conventional disk medium management system. In FIG. 3, the data area 4
Is a unit of several sectors to several tens of sectors on the disk medium and forms a cluster. The file allocation table 3 has a one-to-one correspondence with the data area 4. The directory 2 contains a pointer to the beginning of the file allocation table 3 to be used.

Next, the operation of this conventional example will be described. When reading an arbitrary file existing in the directory 2, first, the corresponding file allocation table 3 is derived from the pointer in the directory 2.
Then, one cluster of the data area 4 corresponding to the file allocation table 3 is derived and the file is read. When the data area 4 of a file cannot fit in one cluster, the file allocation table 3 forms a chain, and the data areas 4 of a plurality of clusters can be used. Further, in this type of disk medium management system, the file allocation tables corresponding to deleted files and unused clusters are removed from this chain, and at the same time there is no pointer from the directory. These data area groups are regarded as free areas.

[0005]

In the above-mentioned conventional disk medium management method, when a new file is to be created, it is usually created by forming a chain from the first free cluster that appears. However, when attempting to create a file with a plurality of consecutive clusters, it is necessary to search the file allocation table until a free area equal to or more than the requested number of clusters is found. The time required for this increases as the disk medium becomes larger and the file allocation table also becomes larger. Also, in the conventional disk medium management method, even in the above operation, the first found free cluster is occupied and a chain is formed from it, so it is not possible to search even if there is another free space of just the right size. And the efficiency of using the data area is not good.

[0006]

DISCLOSURE OF THE INVENTION The disk medium management system of the present invention is a disk medium management system for managing the usage status of a data area on one disk medium and the allocation status of files on the medium in a table format. The one disk medium is provided with a bit map area indicating its usage.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a disk medium management system of the present invention, and FIG. 2 is a block diagram of an example of a bitmap area in FIG. The bitmap area 5 is an area for managing the usage status of the disk medium 1 in cluster units from the first cluster to the last cluster of the disk medium 1, placing bit 1 if "used" and placing bit 0 if "unused". Is. The bitmap area 5 expresses the usage status of the disk medium 1 as a reduced image, and is simultaneously updated by the device driver 6 when a file operation such as file creation or file deletion is performed. The bitmap area 5 comprises a boot area 7, a directory / file allocation table area 8 and a data area 9 as shown in FIG.

Next, the operation of this embodiment will be described.
In the disk medium management system of this embodiment, file operations are performed by managing the directory 2, file allocation table 3 and bitmap area 5. Bitmap area 5 is bit 1 if "used" during file operation
However, if it is "unused", bit 0 is written and updated.
When attempting to create a file with a plurality of consecutive clusters, the device driver 6 refers to the bitmap area 5 and the specified number of clusters or more is "unused".
An area in which bits 0 representing 0 are consecutive is searched. A file is created in this area with the result of which the difference between the most requested cluster number and the number of free clusters is the smallest among the search results.

As a result, as compared with the conventional example in which the entire area of the file allocation table 3 is searched for, the bit map area 5 expressing the usage status of the disk medium 1 including the file allocation table 3 in a reduced image. According to the present embodiment, which is referred to in (1), it is possible to significantly reduce the search time for a free area and improve the efficiency of data area use.

[0010]

As described above, according to the present invention, since the bit map area indicating the use status of one disk medium is provided, the search time for the free area of the disk medium can be shortened and the data area can be used efficiently. Has the effect of enabling.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a disk medium management system of the present invention.

FIG. 2 is a configuration diagram of an example of a bitmap area in FIG.

FIG. 3 is a file configuration diagram of an example of a conventional disk medium management method.

[Explanation of symbols] 1 disk medium 2 directory 3 file allocation table 4 data area 5 bitmap area 6 device driver 7 boot area 8 directory / file allocation table area 9 data area

Claims (1)

Claim: What is claimed is: 1. A disk medium management system for managing the usage status of a data area on one disk medium and the allocation status of files on the medium in a table format. Is a disk medium management system characterized by having a bitmap area indicating its usage.