JPS63231547A - Empty area managing system for memory device - Google Patents

Abstract

PURPOSE:To reduce the probability in which information is stored in the non- continuous area of an empty area and to shorten the reading time of the information by storing data to be able to identify whether a block corresponding to respective columns of an empty area control table is being used, or is the head block of an empty area, or is the empty area succeeding to the head block. CONSTITUTION:In respective columns of an empty area control table 2, either of three types of data of the data to show that the corresponding block of a memory device is used, the data to show the number of the blocks of a continuous empty area and the data to show that the block is the block except the head block of the empty continuous area is only stored. Consequently, since it is sufficient for these data to be short, it is sufficient for the time necessary to retrieve a continuous empty area to satisfy the number of the request blocks of the data to be stored into a memory device 1 to be short. When the continuous empty area to satisfy the number of the request blocks exists, the data are not stored to the non-continuous block.

Description

[Detailed Description of the Invention] [Summary] This is a free space management method for a storage device, which includes a free space management table having columns in one-to-one correspondence with a plurality of blocks of a predetermined capacity unit of the storage device, and a free space management table for each column. is the probability that information is stored in a discontinuous area of an empty area by storing data that can identify whether the corresponding block is in use, the first block of an empty area, or the empty area following the first block. This reduces the time required to read information.

[Industrial application field]

The present invention relates to a free space management method for a storage device, and in particular, it improves the speed of writing and reproducing information to a storage device by managing the free space of a storage device such as a hard disk or floppy disk as a continuous area. Regarding empty space management methods.

The read time of external storage devices such as disk devices is required to be continuous, but for this purpose it is desirable to store information in a continuous area of the storage device. It is necessary to manage the area as a continuous area.

[Conventional technology]

A conventional free space management system is shown in FIG.

In FIG. 6, 61 is a disk, and its description It
The IISjf area is divided into sectors, and sectors in use, that is, sectors in which useful data is stored, are shown with diagonal lines. 62 is an empty area information management table. The area of the disk 61 is managed on a sector-by-sector basis, and information on the start position and end position of the empty area is each represented by a cylinder number, track number, and sector number.

When storing data in an empty area of the disk 61, a processing device (not shown) refers to the table 62 and secures empty area for the required number of sectors. That is, when there is a request for the number of sectors required for data storage, the free space information table 62
With reference to the requested capacity from the beginning of the free space position,
Provides empty space for new data regardless of whether sectors are contiguous or discontinuous. In the illustrated example, when the number of required sectors is 2, for example, data is stored discontinuously in one sector, which is the full capacity of empty area position ■, and in sector 2 of empty area position ■.

[Problem that the invention seeks to solve]

As mentioned above, according to the conventional method, even though there is an empty area with a continuous capacity of the required number of sectors, data may be stored in discontinuous areas, and data may be stored discontinuously. There is a problem in that the time required to read the data increases when the data is read.

Furthermore, each column of the free space information table 62 stores the cylinder number, track number, and sector number as described above. For example, if each of the above numbers is expressed in 1 byte, it is the starting position of the free space. There is a problem in that a total of 6 bytes of data is required to represent the end position, and the storage area occupied by the free space information table 62 is large.

Furthermore, since the data indicating each number in the free space information table 62 is long, when storing data in the free space of the disk 61, the difference between the number of sectors requested for new data and the amount of data in the free space information table 72 is There is also the problem that the time required for the calculation becomes longer, and therefore the processing time for data storage becomes longer.

[Means for solving problems]

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

In FIG. 1, the free space management method for a storage device according to the present invention has a column that corresponds one-to-one to each block when the information storage area of the storage device l is divided into a plurality of blocks each having a predetermined capacity unit. A free space management table 2 is provided.

Each column of the free space management table 2 stores data indicating the usage status of the corresponding block of the storage device.

The data indicating the usage status indicates that the corresponding block is in use.
For one or more consecutive empty areas of a storage device, data i indicating the number of consecutive empty area blocks is placed in the column corresponding to the first block of the empty area. , and data b indicating that the block is an empty area is stored in columns corresponding to blocks in other empty areas.

The free space management method of the present invention further calculates the number of blocks to be searched in accordance with the instruction of the free space search capacity of the storage device 1, and refers to the free space management table 2 to create a free space that is equal to or greater than the calculated number of search blocks. After searching for an area block and storing information in the empty area, the empty area search processing unit 3 updates the empty area management table 2, and the storage device 1 is updated according to the search result by the empty area search processing unit 3. A storage/release processing unit 4 stores information in the searched free space block and releases blocks in use to free space as necessary, and a storage/release processing unit 4 performs storage or release processing. A management table update processing unit 5 updates the free space management table accordingly.
It is equipped with

[For production]

Each column of the free space management table 2 contains data indicating that the corresponding block of the storage device is in use, data indicating the number of consecutive free space blocks, and data indicating that the block other than the first block of the continuous free space is in use. Only one of three types of data indicating a certain thing is stored, and these data only need to be short, so the storage device 1
The time required to search for a continuous empty area that satisfies the required number of blocks for data to be stored in is shortened.

Furthermore, if there is a continuous empty area that satisfies the required number of blocks, data will not be stored in discontinuous blocks.

〔Example〕

FIG. 2 shows the state of the disk device 21 and the free space management table 22 in the free space management system according to an embodiment of the present invention.
It is a figure showing the correspondence with the state.

In FIG. 2, block 0 of the disk drive y122 is an empty area, block 1 is in use, blocks 2 to 4 are empty areas,
Block 4 is in use and blocks 5-8 are empty areas. Each block corresponds to a 256-byte sector, for example. Columns 0 and 1 of empty space management table 22
,2. ... are blocks 0.1, 2, . . . of the disk device 21, respectively. ...There is a one-on-one correspondence. In the free space management table 22, column 0 stores a flag 1'' indicating that block 0 of the disk 21 is the first block of free space and the number of consecutive blocks of free space is 1. Column 1 stores a flag -1 indicating that the corresponding block 1 is in use. Column 2 stores a flag -1 indicating that the corresponding block 2 is the top block of the empty area and , a flag "2" indicating that the number of consecutive empty area blocks is 2 is stored.

Column 3 stores a flag "0" indicating that the corresponding block 3 is an empty area that is not the first block of an empty area.Similarly, the flags stored in the column are "-1". When , the corresponding block is an area in use, and when the flag is a number i greater than or equal to 1, it means that the corresponding block is a continuous empty area and the number of consecutive blocks is i, and the flag When is @0'', it means that the corresponding block is an empty area that is not the first block of an empty area.

Starting from the state shown in FIG. 2, FIG. 3 shows changes in the contents of the free space management table when 500 bytes of new data are stored on disk '21, and FIG. The operation of the apparatus shown in the principle block diagram is shown in the flowchart of FIG.

The operation of storing data on the disk 21 and the operation of updating the free space management table 22 will now be described with reference to FIGS. 1, 3, and 4.

The state shown in FIG. 3(a) is the same as the state shown in FIG. Now, when there is a request to store 500 bytes of data to the storage release processing unit 4, the storage release processing unit 4 notifies the empty area search processing unit 3 of the number of bytes to be searched. The free space search processing unit 3 calculates the number of blocks to be searched based on the notified number of search bytes. In this implementation, since the search request is 500 bytes, the number of blocks to be searched is 2 blocks if one block is 256 bytes (see Figure 4).
Step 40).

Next, the empty area search processing unit 3 uses the empty area management table 2.
2 (2 in Figure 1), search for empty area blocks that are greater than or equal to the number of blocks calculated above (=2) (Figure 4, Step 41), and measure whether or not empty areas exist in continuous blocks. (step 42). In the state shown in FIG. 3(a), a flag 2'' is stored in column 3 of the empty area management table 22, and since this flag 2'' matches the calculated number of blocks, it is determined that there is an empty area.

The determination result that there is an empty area is notified from the empty area search processing unit 3 to the storage release processing unit 4 along with the first column number of the empty area. Based on the notification result, the processing unit 4 searches the disk 21 (see Then, data is stored in the searched empty area of the storage device 1). At the same time, immediately before or after this, the processing unit 4 notifies the management table update processing unit 5 of the block number of the block in which the data is stored, and the management table update processing unit 5 responds to the notified block number. Update the flag of the column to -1 (step 43)
. Here, even if data is not stored in all areas of the searched block, the flag of the column corresponding to the block is updated to -1. For example, if 500 bytes of data are stored, the area of block 3 will have 6 bytes left over, but the flag in column 3 will be updated to -1 even in this case.

The state resulting from the above operations is shown in FIG. 3(b).

Only when it is not possible to search for a continuous empty area of the requested number of bytes or more in step 42, an empty area is searched for by combining the discontinuous empty areas in the empty area management table 22 (step 44).

Unlike the conventional method shown in Figure 6, it first searches for the necessary continuous empty area and stores the data there.
The probability that data will be stored in discontinuous blocks becomes extremely small.

Incidentally, even if a block is in use within the disk 21, when the data therein is no longer needed, it must be released into a free area. FIG. 5 is a flowchart showing the operation when such an area release request is made. 1 and 5, when an area release request is made to the storage release processing unit 4 by notifying the block number of the sector to be released, in step 51, the management table update processing unit 5: Update the flag of the block to be released in the free space management table to free space flag -1''.

Next, in step 52, the storage release processing unit 4 notifies the management table update processing unit 5 of the first block number and block number of the released block, and the update processing unit 5 updates the free space management table based on this notification. If the column above the column corresponding to the released block indicates an empty area, the released block and the empty area above it are treated as a continuous empty area, and the flag in the corresponding column is updated.

Next, in step 53, if the lower block of the released block is an empty area, the flag of the corresponding column is updated, with the block made empty in step 52 and the lower block as a continuous empty area. do.

〔Effect of the invention〕

As described above, according to the present invention, a free space management table is provided that has columns in one-to-one correspondence with a plurality of blocks of a predetermined capacity unit of a storage device, and each column includes information indicating whether the corresponding block is in use or not. By storing data that can identify whether it is the first block of an empty area or the empty area following the first block, when new data is stored in the storage device, the continuous empty area necessary to store the data is If it exists, the effect is that data can be stored in a contiguous empty area in a short time, and the time to read the stored data is also short because the storage area is continuous, and furthermore, the data stored in the empty area management table Since the memory may have a small capacity such as a flag, it is possible to shorten the processing time and reduce the storage area.

[Brief explanation of drawings]

Figure 1 is a block diagram of the principle of the present invention. Figure 2 is a diagram showing the correspondence between the disk status and the status of the free area management table in a free area management method according to an embodiment of the present invention. Figure 3 is a new Figure 4 is a flowchart showing the empty area search operation. Figure 5 is a flowchart showing the area release operation. Figure 6 is the conventional empty area search. It is an explanatory diagram of a management method. DESCRIPTION OF SYMBOLS 1... Storage device, 2... Free area management table, 3... Free area search processing section, 4... Storage release processing section, 5... Management table update processing section.

Claims (1)

[Scope of Claims] When the information storage area of the storage device (1) is divided into a plurality of blocks each having a predetermined capacity, an empty space management table (2) is provided which has columns corresponding one-to-one to each of the blocks. , each column of the free space management table (2) stores data indicating the usage status of the corresponding block of the storage device (1), and the data indicating the usage status indicates the usage status of the corresponding block. It identifies whether the area is in use (a) or empty, and for one or more consecutive empty areas of the storage device (1), the column corresponding to the first block of the empty area is data (i) indicating the number of blocks in the empty area to be stored, and data (b) indicating the empty area in columns corresponding to blocks in other empty areas; The number of blocks to be searched is calculated according to the instruction of the search capacity of the free space of the storage device (1), and the free space blocks that are equal to or larger than the calculated number of search blocks are searched by referring to the free space management table (2). At the same time, an empty area search processing unit (3) updates the empty area management table (2) after storing information in the empty area, and the empty area search processing unit (3) updates the storage according to the search result. a storage and release processing unit (4) that stores information in the searched free space block of the device (1) and releases blocks in use to free space as needed; and the storage and release processing unit A free space management method for a storage device, comprising: a management table update processing unit (5) that updates the free space management table (2) in accordance with the storage or release process in (4).