JP2006106810A - File management device, file management method, recording medium, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform at high speed a process for deleting a file so as to achieve high-speed access, thereby avoiding the life of a recording medium from shortening, and facilitating file restoration. <P>SOLUTION: A file management device, which causes files handled by users and directories to be associated with one another on an actual physical disc to form the files and the directories themselves, manages a recording area by dividing the area into a plurality of areas, and manages an unused cluster in each of the areas by means of a chain structure. To delete a file, the cluster of the file is coupled to the rear end of an unused cluster chain. The unused clusters are rearranged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a file management apparatus and a file management system, and more particularly to a file management apparatus and a file management system that configure files and directories themselves by associating files and directories handled by a user on an actual physical disk. Is.

  Conventionally, a FAT (File Allocation Table) file system is known as a method for managing a large amount of data as files. The FAT file system was used in MS-DOS and Windows (registered trademark), but nowadays, in addition to general-purpose OS (Operating System) such as Linux and various Unix (registered trademark), digital cameras, MP3 players, etc. Widely supported by various devices including flexible disks and removable flash memories (CF cards, etc.) such as consumer devices and various measuring instruments. Now, it is a file management method that can be called the de facto standard in removable media.

  FIG. 12 shows an arrangement of a conventional FAT file system. A FAT file system of DOS or Windows (registered trademark) will be described with reference to FIG. The FAT file system includes a boot sector, two FATs, a root directory (directory entry area), and a data area. The same content as FAT1 is recorded in FAT2, and the system functions by referring to FAT2 even if FAT1 is broken.

  The boot sector includes BPB (BIOS Parameter Block), which is the logical structure data of the recording medium, such as the logical sector length, the number of tracks, and the number of sectors per track, and the boot used in DOS and Windows (registered trademark). The strap loader is recorded.

  In the data area, the data body of each file is divided and stored, and managed in units called clusters in which several sectors are grouped. In the FAT, information indicating the configuration of a series of clusters on the data area, that is, the usage status of the clusters is recorded. Therefore, since the divided file data is recorded in units of clusters, the physical positions of the file data on the disk are not continuous.

  The FAT file system is a system in which files and directories on block devices such as flexible disks and hard disks are made to correspond to actual physical disks, and the files and directories themselves are configured, and is managed by information called directory entries and FAT. The

  FIG. 13 shows an example of a conventional FAT entry. In this example, the file starting with FAT entry 2 is recorded in cluster number 2 (0x00000002) in the data area, followed by cluster number 3 (0x00000003), and then cluster number 4 (0x00000004) and 5 (0x00000002). Indicates that data is being recorded. Since 0xFFFFFFFF (EOF mark) is written in the FAT entry 5, this cluster number is the final recording position of the file data. In addition, the clusters 6 to 8 whose FAT entry value is 0x00000000 are unused areas. FAT entries 0 and 1 are reserved areas (RSV marks).

  The cluster number of the FAT entry has a one-to-one correspondence with the cluster in which the file data is divided and recorded, and holds the cluster number that follows each of the set of cluster numbers on the data area constituting the file body. is doing. Therefore, even if the physical positions of the clusters are separated, if the series of FAT cluster numbers are read, the clusters stored in the data area are read in order, and the divided file body can be reconfigured. Is possible. If the FAT entry has no subsequent cluster, that is, if the corresponding cluster is the last cluster of the file, a unique value 0xFFFFFFFF indicating that fact is written. A FAT entry whose value is 0x00000000 means an unused area. However, of the series of cluster numbers of each file, only the first cluster number is written to the directory entry.

  FIG. 14 shows the format of the directory entry recorded in the directory entry area shown in FIG. One directory entry is composed of 32 bytes, and the file name, extension, attribute, update date / time, start cluster, file size, and the like are recorded.

Advantages of the FAT file system include the following.
(1) If the FAT chain is followed in order, the clusters constituting the file can be found one after another, which is suitable for sequential files.
(2) When file management information is read and resident in advance in RAM and it is desired to prevent an excessive seek from occurring during reproduction of audio-video information, information indicating the position information of the file and the root directory are one place as FAT. It is easy to make it resident in RAM. Therefore, not only MS-DOS and Windows (registered trademark) but also many other OSs are often supported.

  On the other hand, the FAT file system has some disadvantages. For example, in Japanese Patent Application Laid-Open No. 4-139543, when a file is newly created, the FAT is assigned in the order of the smallest FAT number among the FATs not used as the FAT for use in the file. If the production is frequently performed, the FAT having a small FAT number is always used, and since only the same part of the recording medium is used, it points out the disadvantage of shortening the life of the recording medium. Furthermore, if the FAT number of the file that has just been deleted is small, the FAT of the file is used by creating a new file next, so that the file cannot be restored. Also pointed out.

  In order to solve this problem, an unused FAT chain is added to the end of the unused FAT chain, and when used, it is used from the beginning of the unused FAT chain. Thus, a file management system that solves the above-described problems has been disclosed (see, for example, Patent Document 1).

  Also, when deleting a file, all FAT entries that had previously retained the identification numbers of the clusters that make up the file must be cleared to 0x00000000, and the operation itself is simple but involves a large number of loops. As a result, it points out the drawback of slow processing. Further, in order to connect a new area to the end of the file, there is a problem that the FAT entries corresponding to the file must be sequentially operated to the end, and a loop having a large number of times must be processed.

  In order to solve the problem, the free area is described and managed by a chain structure like a file, and a free entry or individual file area is represented by providing a pointer to the FAT entry at the end of the file. A file management system that solves the above-described problems simply by cutting and pasting a chain structure is disclosed (for example, see Patent Document 2).

JP-A-4-139543 JP 2001-56774 A

  However, even in the above-described conventional example, further increase in file system speed is required as the capacity of recording media continues year by year and the file size of audio video information to be processed increases. In addition, since the FAT file system is widely supported by various devices and is a de facto standard for removable media, there still remains a problem that further speeding up is necessary.

  The present invention has been proposed in order to solve such problems. The object of the present invention is to perform high-speed file management even in an environment where a sufficiently high-speed CPU cannot be used. It is an object of the present invention to provide a file management apparatus and a file management system that avoids shortening the life of a recording medium due to the use of only the same part, and that makes it easy to restore a file that has just been deleted.

  The present invention has been made to solve the above-described problems. In the present invention, each file data is recorded in a file management method for recording and managing file data on a recording medium composed of unit areas. A data link step for linking and managing the unit areas, a file start recording step for recording a pointer to the first unit area for recording the data of each file, and a last unit for recording the data of each file A file end recording step for recording a pointer to the area, an unused area management step for dividing the recording area of the recording medium into a plurality of areas, and linking unused unit areas for each area, and the division Unused area start recording that records a pointer to the first unit area of an unused unit area managed for each of a plurality of areas And an unused area end recording step for recording a pointer to the last unit area of the unused unit area managed for each of the plurality of divided areas. I will provide a.

  According to the present invention, in the file management apparatus and the file management method, it is possible to perform a file deletion process at a high speed by managing unused clusters in the recording area with a chain structure, and further, the recording area is divided into a plurality of recording areas. Management of unused clusters in a chain structure for each recording area, thereby preventing the recording area from being dispersed and enabling high-speed access to recording media such as disk devices It is possible to provide a file management method.

  Also, in each area, the cluster used for the deleted file is joined to the end of the chain structure of the unused cluster, and when used, it is used from the beginning of the chain structure. By recording data in a recording area that is used less frequently in the area, it is possible to avoid shortening the life of the recording medium by using only the same part of the recording medium and to easily restore the file that has just been deleted A management device and a file management method can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall system configuration of an information processing apparatus that is a file management apparatus according to an embodiment of the present invention.
In the figure, a CPU 101 controls the entire file management apparatus 100. The main memory 105 is loaded with a program executed by the CPU 101. The graphic controller 107 controls display on the display 108.

  The north bridge 103 is a bridge for connecting a CPU local bus 102, a memory bus 104, an AGP (Accelerated Graphics Port) bus 106, and a PCI (Peripheral Component Interconnect) bus 109. The south bridge 110 is a bridge that connects ATA (AT Attachment) buses 111 and 113, a PCI bus 119, and an LPC (Low Pin Count) bus 115.

  The disk device 112 records various programs (operating system, device driver, application program, etc.) executed by the CPU 101 and various management information. The program recorded on the disk device 114 is loaded into the main memory 105 as necessary. Various data and contents are recorded on the disk device 114.

  The keyboard controller 116 controls a key input operation using the keyboard 117. The BIOS-ROM 118 records an initial program loader (Initial Program Loader).

  A NIC (Network Interface Card) 120 is connected to the PCI bus 119. The NIC 120 connects the recording apparatus 100 to a network (for example, a LAN).

Next, a FAT file file system applied to the disk device 114 will be described with reference to FIGS.
FIG. 2 is an example showing the structure of the FAT 201. The FAT 201 includes a FAT header 202 and a plurality of FAT entries 204 corresponding to the respective clusters.

  The FAT header 202 includes a recording area management table 203 when managing the recording area by dividing it into a plurality of parts (N divisions in this embodiment). The recording area management table 203 includes an unused cluster start pointer 205, an unused cluster end pointer 206, a cluster access count 207, a recording area start pointer 208, a recording area end pointer 209, and a used cluster number 210 for each recording area. included.

  The recording area start pointer 208 and the recording area end pointer 209 indicate which cluster area is managed among the divided recording areas. For example, in the example of FIG. 2, the recording area of FAT number 2 to FAT number M is divided into N, the recording area start pointer 208 of the divided first recording area is 2, and the recording area end pointer is M / N. Yes. That is, the first recording area is from the cluster of FAT number 2 to the cluster of FAT number M / N. Similarly, the recording area start pointer 208 of the divided second recording area is M / N + 1, and the recording area end pointer is 2 × M / N. That is, the second recording area is from the cluster of FAT number M / N + 1 to the cluster of FAT number 2 × M / N. In the present embodiment, the natural number M is an integer multiple of the natural number N.

  In the unused cluster start pointer 205, a FAT number indicating the first cluster of a series of unused clusters in which no data is recorded in the divided recording area is recorded. When there is no unused cluster, 0xFFFFFFFF is recorded in the unused cluster start pointer 205. Similarly, in the unused cluster end pointer 206, a FAT number indicating the last cluster of a series of unused clusters in which no data is recorded in the divided recording area is recorded. If there is no unused cluster, 0xFFFFFFFF is also recorded in the unused cluster end pointer 206.

  In the example of FIG. 2, the unused cluster start pointer 205 and the unused cluster end pointer 206 of the divided first recording area are M / N. That is, the cluster of FAT number 6 is the head of a series of unused clusters, and the cluster of FAT number M / N is the last of a series of unused clusters. Similarly, in the divided second recording area, the unused cluster start pointer 205 is M / N + 4, and the unused cluster end pointer 206 is 2 × M / N. That is, the cluster having the FAT number M / N + 4 is set as the head of the series of unused clusters, and the cluster having the FAT number 2 × M / N is set as the tail end of the series of unused clusters.

  The cluster access count 207 is a counter that counts accesses to the divided recording areas in units of clusters. In the example of FIG. 2, the number of cluster accesses 207 to the divided first recording area is 200. That is, it has already been accessed 200 times. Similarly, the number of cluster accesses 207 to the divided second recording area is set to 4000. That is, it has already been accessed 4000 times.

  The number of used clusters 210 records the number of clusters currently used in the divided recording area. In the example of FIG. 2, the number of used clusters 210 of the divided first recording area is four. That is, there are four clusters currently used. Similarly, the number of used clusters 210 of the divided second recording area is set to 3. That is, there are three clusters currently used.

  The FAT entry 204 is assigned the same FAT number as the cluster number assigned to the corresponding cluster. For example, FAT number 2 is assigned to the FAT entry 204 corresponding to cluster number 2. In the FAT pointer, a FAT number assigned to the cluster, which is connected to the rear of the cluster, is recorded. When there is no cluster behind, that is, when the corresponding cluster is the end of the file, 0xFFFFFFFF is recorded in the FAT pointer.

  For example, when only one file is recorded on the disk device 114 in four clusters assigned with FAT numbers 2, 3, 4, and 5, as shown in FIG. , FAT number 3 (0x00000003) assigned to the cluster connected backward is recorded. In the FAT pointer of FAT number 3, FAT number 4 (0x00000004) assigned to the cluster connected backward is recorded. The same is recorded in the FAT pointer of FAT number 4. In the FAT pointer of FAT number 5, 0xFFFFFFFF indicating that there is no cluster connected backward is recorded.

  FIG. 3 shows a state in which one file is recorded in four clusters to which FAT numbers 2, 3, 4, and 5 are assigned. A size recording area 301 for recording information on the size of the file is provided in the first cluster of the file (in the example of FIG. 3, the cluster of FAT number 2). File data is recorded after the second cluster (the cluster of FAT number 3 in the example of FIG. 3). Note that the size recording area 301 may be provided in the directory entry, and the file data may be recorded from the first cluster.

  FIG. 4 shows a configuration example of the size recording area 301. In the size recording area 301, a final FAT number recording area 401 and an occupied cluster number recording area 402 are provided. In the final FAT number recording area 401, the FAT number (5 in the example of FIG. 3) of the last cluster of the file is recorded. In the occupied cluster number recording area 402, the number of clusters used by the file, that is, the sum of the clusters in which the size recording area 301 is recorded and the clusters in which data is recorded (4 in the example of FIG. 3) is recorded.

Next, file creation processing, file deletion processing, and unused cluster rearrangement processing using FAT will be described with reference to the flowcharts of FIGS.
First, file creation processing will be described with reference to the flowcharts of FIGS.

  At the time of creating the file, the area where the data is recorded is selected (step S501). That is, the recording area to be recorded is selected from among the N divided recording areas. This recording area selection process will be described with reference to the flowchart of FIG.

  First, X and Y are initialized (step S601). That is, 1 is substituted into X and Y.

  Next, it is checked whether the number of accesses to the Xth recording area is the Yth smallest (step S602). That is, the cluster access count 207 in the management table 203 of each divided recording area is compared and checked. Since X and Y are both 1 at first, whether or not the number of accesses to the first recording area is the first is compared with the number of cluster accesses 207 in other recording areas. As a result of the check, if it is determined that the number of accesses to the Xth recording area is not the Yth smallest, the process proceeds to step S605. If it is determined that the number of accesses to the Xth recording area is the Yth smallest, the process proceeds to step S603.

  In step S605, the value of X is incremented by 1, and the process proceeds to step S602. That is, the next recording area is checked. Accordingly, the recording area with the Yth smallest number of accesses is obtained by looping through steps S602 and S605.

  In step S603, it is checked whether there is a sufficient unused recording area in the Xth recording area. Normally, if one cluster is unused, it is determined that there is sufficient unused recording area. However, in the divided recording area, if you want to secure and record multiple areas from the same recording area, Check if there are unused recording areas for the number of clusters. Regarding the presence / absence of an unused recording area, the difference between the recording area end pointer 209 and the recording area start pointer 208 is the number of clusters included in the recording area, so the number of clusters obtained by subtracting the number of used clusters 210 from the number of clusters is: Calculated as the number of unused clusters. If it is determined that there is not enough unused recording area in the Xth recording area, the process proceeds to step S606. If it is determined that there is a sufficient unused recording area in the Xth recording area, the process proceeds to step S604.

  In step S606, the value of Y is incremented by 1, and X is initialized, that is, 1 is substituted for X, and the process proceeds to step S607.

  In step S607, it is checked whether the value of Y is greater than N. If the value of Y is not greater than N, the process proceeds to step S602. If the value of Y is greater than N, the process proceeds to step S608. Therefore, a recording area having a sufficient unused area is obtained by looping step S602, step S603, step S606, and step S607.

  In step S608, assuming that there is no sufficient unused recording area, the process ends, and the process returns to FIG.

  In step S604, the Xth recording area is selected, the process ends, and the process returns to FIG. That is, it is determined that the number of accesses to the Xth recording area is small and a sufficient unused recording area can be secured, the Xth recording area is selected, and the process returns to FIG.

  In the recording area selection in step S501 of FIG. 5, if there is not a sufficient unused recording area, the process is terminated. Alternatively, if it is determined that a sufficient unused recording area can be secured, the processing from step S502 is performed on the selected Xth recording area.

  In step S502, an unused cluster A is acquired. That is, the FAT number corresponding to the unused cluster is acquired from the recording area selected in step S501. This unused cluster A acquisition process will be described with reference to the flowchart of FIG.

  First, the unused cluster start pointer 205 in the management table 203 of the selected recording area is read and substituted for K (step S701). For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster start pointer 205 is 6, so 6 is substituted for K.

  Next, it is checked whether K is 0xFFFFFFFF (step S702). That is, it is checked whether 0xFFFFFFFF is recorded in the unused cluster start pointer of the management table 203 of the selected recording area and there is no unused cluster. If K is 0xFFFFFFFF, that is, if all the clusters in the selected recording area are used or cannot be used, it is determined that there is no unused cluster and the process proceeds to step S707. If K is not 0xFFFFFFFF, that is, if there is an unused cluster, the process proceeds to step S703.

  In step S707, since there is no unused cluster and it cannot be acquired, the process ends and the process returns to FIG.

  In step S703, the FAT pointer of FAT number K is read and substituted for L. For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster start pointer 205 is 6, so the FAT pointer 0x00000007 with FAT number 6 is read and 7 is substituted into L.

  Next, L is recorded in the unused cluster start pointer 205 of the management table 203 of the selected recording area (step S704). For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster start pointer 205 is 6, and the FAT pointer of FAT number 6 is 0x00000007. 7 is newly recorded.

  Next, the number of used clusters 210 in the management table 203 for the selected recording area is incremented by 1 (step S705). For example, in the example of FIG. 2, if the first recording area is selected, the number of unused clusters 210 is incremented by 1, and 4 to 5 are newly recorded.

  Next, it is assumed that the unused cluster K has been acquired, the FAT number K is set as a return value, the process is terminated, and the process returns to FIG. 5 (step S706). For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster start pointer 205 is 6, so the cluster of FAT number 6 is acquired as an unused cluster, and the process returns to FIG.

  In the unused cluster A acquisition process in step S502 of FIG. 5, if an unused cluster cannot be acquired, the process ends. Alternatively, if an unused cluster can be acquired, the FAT number of the acquired cluster is substituted into A. That is, K in FIG. 7 is substituted into A in FIG. 5, and the processing after step S503 is performed. For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster start pointer 205 is 6, so that the cluster of FAT number 6 is acquired as an unused cluster, and 6 is substituted for A. Is done.

  In step S503, A is recorded in the start cluster of the directory entry of the file to be created. That is, the fact that the FAT number of the cluster which is the head of the file is A is recorded. For example, in the example of FIG. 2, if the first recording area is selected, 6 is recorded in the starting cluster of the directory entry.

  Next, an unused cluster B is acquired (step S504). That is, the FAT number corresponding to the unused cluster is acquired from the recording area selected in step S501. Since this unused cluster B acquisition process is the same as that in step S502, a description thereof will be omitted. If an unused cluster cannot be acquired, the process proceeds to step S513. Alternatively, if an unused cluster can be acquired, the FAT number of the acquired cluster is substituted for B. That is, K in FIG. 7 is substituted into B in FIG. 5, and the process proceeds to step S505. For example, in the example of FIG. 2, if the first recording area is selected, a cluster with FAT number 7 is acquired as an unused cluster, and 7 is substituted for B.

In step S513, cluster A is released. In other words, because the second unused cluster could not be acquired and the file creation failed,
In step S502, unused clusters that have already been acquired are released. The cluster A release process will be described with reference to the flowchart of FIG. In the flowchart of FIG. 8, the cluster that performs the release process is D. That is, when the processing is shifted to the flowchart of FIG. 8, the processing is performed by substituting A in FIG. For example, in the example of FIG. 2, if the first recording area is selected, the FAT number of the acquired cluster A is 6, and if the unused cluster B cannot be acquired in step 504, The cluster of FAT number 6 is released. In other words, in FIG. 8, the cluster 6 is released, and D becomes 6.

  First, the unused cluster end pointer 206 in the management table 203 of the selected recording area is read and substituted into E (step S801). For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster end pointer 206 is M / N, and therefore M / N is substituted for E.

  Next, D is recorded in the FAT pointer of FAT number E (step S802). For example, in the example of FIG. 2, if the first recording area is selected, the unused cluster end pointer 206 is M / N, so D, that is, 0x00000006 is recorded in the FAT pointer of the FAT number M / N. .

  Next, 0xFFFFFFFF is recorded in the FAT pointer of FAT number D (step S803). For example, in the example of FIG. 2, if the first recording area is selected, since D is 6, 0xFFFFFFFF is recorded in the FAT pointer of FAT number 6.

  Next, D is recorded in the unused cluster end pointer 206 of the management table 203 of the selected recording area (step S804). For example, in the example of FIG. 2, if the first recording area is selected, D is 6, so 6 is recorded in the unused cluster end pointer 206 of the management table 203 of the first recording area.

  Next, the number of used clusters 210 in the management table 203 for the selected recording area is decremented by 1 (step S805). For example, in the example of FIG. 2, if the first recording area is selected, the number of used clusters 210 in the management table 203 of the first recording area is equal to the unused cluster A acquisition process in step S502 of FIG. In step S705 in FIG. 7, the number of used clusters is incremented by 1 and recorded from 4 to 5, in this step S805, is decremented by 1 and recorded from 5 to 4, and the cluster D release processing in FIG. Return to FIG.

  In step S514, the directory entry start cluster is cleared and the process ends. That is, in step S503, the fact that A is recorded in the start cluster of the directory entry of the created file is cleared and the process ends. Here, as the file creation error, the directory entry itself of the file to be created may be cleared.

  In step S505, C is initialized, that is, the acquired number of clusters is substituted into C. Since two clusters are acquired in step S502 and step S504, 2 is substituted for C.

  Next, B is recorded in the FAT pointer of FAT number A (step S506). That is, the cluster A and the cluster B are connected. For example, in the example of FIG. 2, if the first recording area is selected, A is 6 and B is 7 at the first time point, so 0x00000007 is recorded in the FAT pointer of FAT number 6.

  Next, 0xFFFFFFFF is recorded in the FAT pointer of FAT number B (step S507). That is, the FAT number B is recorded as a temporary final cluster of the new file. For example, in the example of FIG. 2, if the first recording area is selected, B is 0x00000007 at the first time point, so 0xFFFFFFFF is recorded in the FAT pointer of FAT number 7.

  Next, the data of the new file is recorded in the cluster of FAT number B, and the cluster access count 207 in the management table 203 of the selected recording area is incremented by 1 (step S508). For example, in the example of FIG. 2, if the first recording area is selected, since B is 0x00000007 at the first time, the data of the new file is recorded in each sector of the cluster of FAT number 7, and the number of cluster accesses 207 is incremented by 1, and 200 to 201 are newly recorded.

  Next, it is checked whether or not there is remaining data not yet recorded in the recording data (step S509). That is, in step S508, it is checked whether or not there is subsequent data for the recorded file data. If there is subsequent data, the process proceeds to step S510. If there is no subsequent data, the file creation is terminated, and the process proceeds to step S515.

  In step S510, B is substituted into A. If the first recording area is selected, since B is 0x00000007 at the first time point, 7 is substituted into A.

  Next, an unused cluster B is acquired (step S511). That is, the FAT number corresponding to the unused cluster is acquired from the recording area selected in step S501. Since this unused cluster B acquisition process is the same as that in step S502, a description thereof will be omitted. If an unused cluster cannot be acquired, the process proceeds to step S515. Alternatively, if an unused cluster can be acquired, the FAT number of the acquired cluster is substituted for B. That is, K in FIG. 7 is substituted into B in FIG. 5, and the process proceeds to step S512. For example, in the example of FIG. 2, if the first recording area is selected, a cluster having the FAT number 0x00000008 is acquired as an unused cluster at the first time, and 8 is substituted for B.

  In step S512, C is incremented by 1, and the process proceeds to step S506. At the first time point, since 2 is substituted for C in step S505, 2 to 3 are substituted. Accordingly, the loop from step S506 to step S512 is repeatedly performed while the remaining data to be recorded in the new file exists and an unused cluster can be acquired.

  In step S515, B is recorded as the final FAT number in the final FAT number recording area 401 of the size recording area 301. That is, when the file is created, the FAT number of the cluster in which the last data of the file is recorded is recorded in the final FAT number recording area 401.

  Next, C is recorded as the occupied cluster number in the occupied cluster number recording area 402 of the size recording area 301 (step S516). That is, the total number of clusters used for the data recording and size recording area of the file is recorded in the occupied cluster number recording area 402.

  Next, the cluster access count 207 in the management table 203 for the selected recording area is incremented by 2 (step S517). However, when step S515 and step S516 are processed simultaneously, the cluster access count 207 is incremented by one.

Next, various data such as a file size is recorded in the directory entry, and the process ends (step S518).
The above is the description of the process for the file creation process.

Next, the file deletion process will be described with reference to the flowchart of FIG.
First, the start cluster of the directory entry of the file to be deleted is read and assigned to S (step S901). For example, in the example of FIG. 2, when deleting a file recorded in the clusters of FAT numbers 2, 3, 4, and 5, FAT number 2 is recorded in the starting cluster of the directory entry, and 2 is substituted for S. The

  Next, the unused cluster end pointer 206 of the divided recording area management table 203 to which the cluster of the FAT number S belongs is read and substituted into T (step S902). For example, in the example of FIG. 2, when deleting a file recorded in the clusters of FAT numbers 2, 3, 4, and 5, the cluster of FAT number 2 belongs to the first recording area, and management of the first recording area is performed. Since the unused cluster end pointer 206 of the table 203 is M / N, M / N is substituted for T.

  Next, S is recorded in the FAT pointer of FAT number T (step S903). For example, in the example of FIG. 2, when deleting a file recorded in a cluster of FAT numbers 2, 3, 4, and 5, since 2 is substituted for S and M / N is substituted for T, FAT number M 0x00000002 is recorded in the / N FAT pointer.

  Next, the final FAT number recorded in the final FAT number recording area 401 of the size recording area 301 is read and substituted into U (step S904). For example, in the example of FIG. 2, when deleting a file recorded in the clusters of FAT numbers 2, 3, 4, and 5, the FAT number of the cluster that recorded the last data of the file is 5, and the last FAT number record It is recorded in area 401. Therefore, 5 is assigned to U.

  Next, U is recorded in the unused cluster end pointer 206 of the management table 203 of the divided recording area to which the cluster of the FAT number S belongs (step S905). For example, in the example of FIG. 2, when deleting a file recorded in a cluster with FAT numbers 2, 3, 4, and 5, the cluster with FAT number 2 belongs to the first recording area and is assigned to U. Since the FAT number of the cluster in which the last data is recorded is 5, 5 is recorded in the unused cluster end pointer 206 of the management table 203 of the first recording area.

  Next, the occupied cluster number recorded in the occupied cluster number recording area 402 of the size recording area 301 is read and substituted into T (step S906). For example, in the example of FIG. 2, when deleting a file recorded in the clusters of FAT numbers 2, 3, 4, and 5, the number of clusters in which file data is recorded is 4, and the occupied cluster number recording area 402 Is recorded. Therefore, 4 is substituted for T.

  Next, a value obtained by subtracting T from the number of used clusters 210 of the divided recording area management table 203 to which the cluster of the FAT number S belongs is recorded (step S907). For example, in the example of FIG. 2, when deleting a file recorded in a cluster with FAT numbers 2, 3, 4, and 5, the cluster with FAT number 2 belongs to the first recording area and is assigned to T. Since the number of clusters in which the data is recorded is 4, the value recorded in the number of used clusters 210 in the management table 203 of the first recording area, that is, 4 is subtracted from 4, and 0 is newly recorded. . That is, it means that no cluster is used in the first recording area.

  Next, the cluster access count 207 in the management table 203 of the divided recording area to which the cluster of the FAT number S belongs is incremented by 2 (step S908). However, when step S904 and step S906 are processed simultaneously, the cluster access count 207 is incremented by one.

  For example, in the example of FIG. 2, when deleting a file recorded in the clusters of FAT numbers 2, 3, 4, and 5, since the cluster of FAT number 2 belongs to the first recording area, The cluster access count 207 in the management table 203 is incremented.

Next, the directory entry of the file to be deleted is cleared, and the process ends (step S909).
The above is the description of the process regarding the file deletion process.

Next, the unused cluster rearrangement process will be described with reference to the flowcharts of FIGS. 10 and 11.
First, F is initialized (step S1001). That is, 1 is substituted into F.

  Next, it is checked whether the value of F is larger than N (step S1002). If the value of F is not greater than N, the process proceeds to step S1003. If the value of F is greater than N (1), the process proceeds to step S1101 in FIG.

  In step S1003, the unused cluster start pointer 205 in the management table 203 for the Fth recording area is read and substituted for G. For example, in the example of FIG. 2, F is 1, that is, regarding the first recording area, initially, the unused cluster start pointer 205 of the management table 203 is 6, and 6 is substituted for G.

  Next, the FAT pointer of FAT number G is read and substituted for H (step S1004). For example, in the example of FIG. 2, F is 1, that is, regarding the first recording area, initially, the unused cluster start pointer 205 of the management table 203 is 6, and 6 is assigned to G. 6 FAT pointer 0x00000007 is assigned to H.

  Next, a temporary value indicating 0x00000000, which is an unused area, is recorded in the FAT pointer of FAT number G (step S1005). For example, in the example of FIG. 2, F is 1, that is, regarding the first recording area, initially, the unused cluster start pointer 205 of the management table 203 is 6, and 6 is assigned to G. 0x00000000 is recorded in the FAT pointer 6.

  Next, it is checked whether the value of H substituted in step S1004 is 0xFFFFFFFF (step S1006). If the value of H is 0xFFFFFFFF, the process proceeds to step S1008, and if the value of H is not 0xFFFFFFFF, the process proceeds to step S1007. That is, with respect to a series of unused clusters in the Fth recording area, it is checked whether 0x00000000 has been recorded in all FAT pointers.

  In step S1007, the value of H is substituted for G, and the process proceeds to step S1004. For example, in the example of FIG. 2, F is 1, that is, regarding the first recording area, initially, the unused cluster start pointer 205 of the management table 203 is 6. In step S1004, the FAT pointer 0x00000007 of FAT number 6 is set. Since 7 is assigned to H, 7 is assigned to G. Therefore, by looping from step S1004 to step S1007, 0x00000000 is recorded in all FAT pointers for a series of unused clusters in the Fth recording area.

  In step S1008, the value of F is incremented by 1, and the process proceeds to step S1002. Therefore, by looping from step S1002 to step S1008, 0x00000000, which temporarily indicates that it is unused, is recorded in all FAT pointers in a series of unused clusters for all the recording areas divided into N. To do.

In step 1101, F is initialized. That is, 1 is substituted into F.
Next, F is initialized (step S1001). That is, 1 is substituted into F.
Next, it is checked whether the value of F is greater than N (step S1102). If the value of F is not greater than N, the process proceeds to step S1103. If the value of F is greater than N, it is determined that the rearrangement process for all unused clusters has been completed, and the process ends.

  In step S1103, the unused cluster start pointer 205 of the F-th recording area management table 203 is read and substituted for G, H, and I. For example, in the example of FIG. 2, F is 1, that is, for the first recording area, the unused cluster start pointer 205 of the management table 203 is 6 at first, and 6 is substituted for G, H, and I.

  Next, it is checked whether the value of H is equal to the value recorded in the recording area end pointer 209 of the Fth recording area management table 203 (step S1104). If the value of H is equal to the value recorded in the recording area end pointer of the F-th recording area management table 203, the process proceeds to step S1106, and if not equal, the process proceeds to step S1105.

In step S1105, the value of H is incremented by 1, and the process proceeds to step S1107. In other words, the subsequent processing is performed for the FAT pointer having one FAT number.
In step S1106, the value recorded in the recording area start pointer 208 of the management table 203 for the Fth recording area is read and substituted, and the process proceeds to step S1107. That is, the subsequent processing is performed on the FAT pointer for the first FAT number in the Fth recording area.

  In step S1107, it is checked whether the value of H is equal to the value of I. That is, it is compared with the value of the unused cluster start pointer 205 in the management table 203 of the Fth recording area set to I in step S1103, and it is checked whether the processing has been completed for the Fth recording area. If the value of H is equal to the value of I, the process proceeds to step S1112, and if not equal, the process proceeds to step S1108.

In step S1108, the FAT pointer with FAT number H is read and substituted for J.
Next, it is checked whether or not the value of J is 0x00000000 (step S1109). That is, it is checked whether 0x00000000 is temporarily recorded in the FAT pointer of FAT number H, indicating that it is unused. If the value of J is 0x00000000, the process proceeds to step S1110, and if it is not 0x00000000, the process proceeds to step S1104. Steps S1104 to S1109 are looped until it is determined in step S1107 that the processing has been completed for the Fth recording area, or until a FAT number tentatively shown to be unused is found.

In step S1110, H is substituted into the FAT pointer of FAT number G. That is, the unused cluster before the FAT number G and the unused cluster of the FAT number H are connected.
Next, the value of H is substituted into G, and the process proceeds to step S1104 (step S1111). Therefore, by looping from step S1104 to step S1111, the unused clusters are rearranged in the Fth recording area.

  In step S1112, 0xFFFFFFFF is recorded in the FAT pointer of FAT number G. That is, it is recorded that the cluster having the FAT number G is the last cluster in a series of unused clusters.

Next, G is recorded in the unused cluster end pointer 206 of the F-th recording area management table 203 (step S1113).
Next, the value of F is incremented by 1, and the process proceeds to step S1102 (step S1114). That is, regarding the Fth recording area, rearrangement of unused clusters and correction of the management table 203 are terminated, and the process proceeds to the next recording area. By repeating the processing from step S1102 to step S1114, the unused clusters are rearranged in all the recording areas.

This completes the description of the processing for rearranging unused clusters.
The unused cluster rearrangement process may be performed at the time of defragmentation for eliminating fragmentation in the recording area, or may be performed when a load is not applied to the system such as the CPU.

  Further, in the present embodiment, in order to reduce seek time as much as possible in a recording medium such as a hard disk device, which is one of the purposes, a configuration in which one file is not recorded across a plurality of recording areas is provided. However, a configuration in which recording can be performed across a plurality of recording areas may be adopted.

  In that case, when there is no unused cluster in FIG. 7, it can be realized by selecting the recording area shown in FIG. 6 again. Specifically, the FAT number of the start cluster in the recording area at the time of recording in the other recording area in the size recording area 301 shown in FIG. 4, the recording area at the end of recording in the other recording area The FAT number of the end cluster and the occupied cluster in the recording area are recorded, and when deleting the file, the same processing as in FIG. 9 is performed on the management table 203 and the FAT entry of the recording area using the information. Can be realized. In this case, there is no need to change the unused cluster rearrangement process shown in FIGS. 10 and 11.

  In the present embodiment, as shown in FIG. 3, a size recording area 301 for recording information on the file size is provided in the first cluster of the file, and the actual data of the file is recorded in the second and subsequent clusters. However, the size recording area 301 may be recorded in a directory entry or other location, and the actual data of the file may be recorded from the top cluster.

  Further, although the number of clusters used for file recording is recorded in the occupied cluster number recording area 402 of the size recording area 301, the number of clusters may be obtained from the file size of the directory entry.

  Further, the recording area start pointer 208 and the recording area end pointer 209 of each divided recording area are included in the recording area management table 203, but a value obtained by dividing the number of clusters in the entire recording area by the number of divisions is used. The boundaries may be separated.

  In the above-described embodiment, the file management apparatus 100 shown in FIG. 1 realizes the function by reading out a program for realizing the function of each process shown in FIGS. However, the present invention is not limited to this, and all or part of the functions of each process may be realized by dedicated hardware. The above-mentioned memory is a non-volatile memory such as a magneto-optical disk device or a flash memory, a recording medium such as a CD-ROM that can only be read, a volatile memory other than a RAM, or a computer read by a combination thereof. The recording medium may be a writable recording medium.

  Further, a program for realizing the functions of the processes shown in FIGS. 5 to 11 of the file management apparatus 100 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system. Each process may be performed by executing. Here, the “computer system” includes an OS and hardware such as peripheral devices. Specifically, a program read from a recording medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, and then the program is read based on the instructions of the program. It includes the case where the CPU of the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  The “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as a hard disk built in the computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding a program for a certain period of time are also included.

The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

Further, a program product such as a computer-readable recording medium in which the above program is recorded can also be applied as an embodiment of the present invention. The above program, recording medium, transmission medium, and program product are included in the scope of the present invention.
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

It is a block diagram of the whole system of the file management apparatus which concerns on this embodiment. 3 is a diagram illustrating an example of a configuration of a FAT 201. FIG. It is a figure which shows an example of file recording. 3 is a diagram illustrating a configuration of a size recording area 301. FIG. It is a flowchart explaining a file creation process. It is a flowchart explaining a recording area selection process. It is a flowchart explaining the acquisition process of an unused cluster. 10 is a flowchart for explaining a cluster D release process. It is a flowchart explaining a file deletion process. It is a flowchart explaining the rearrangement process of an unused cluster. It is a flowchart explaining the rearrangement process of an unused cluster. It is a figure which shows the structure of the conventional FAT file system. It is a figure which shows an example of the conventional FAT entry. It is a format figure of a directory entry.

Explanation of symbols

100 File management apparatus 101 CPU
102 CPU local bus 103 North bridge 104 Memory bus 105 Main memory 106 AGP (Accelerated Graphics Port) bus 107 Graphic controller 108 Display 109, 119 PCI (Peripheral Component Interconnect) bus 110 South bridge 111, 113 ATA (AT Attachment) bus 112, 114 Disk device 115 LPC (Low Pin Count) bus 116 Keyboard controller 117 Keyboard 118 BIOS-ROM
120 NIC (Network Interface card)
201 FAT (File Allocation Table) entry 202 FAT header 203 Recording area management table 204 FAT header 205 Unused cluster start pointer 206 Unused cluster end pointer 207 Cluster access count 208 Recording area start pointer 209 Recording area end pointer 210 Number of used clusters 301 Size recording area 401 Final FAT number recording area 402 Occupied cluster number recording area

Claims (12)

In a file management apparatus for recording and managing file data on a recording medium composed of unit areas,
A data link means for linking and managing each unit area for recording file data;
File start recording means for recording a pointer to the head unit area for recording data of each file;
File end recording means for recording a pointer to the last unit area for recording data of each file;
An unused area management unit that divides a recording area of a recording medium into a plurality of areas and links and manages unused unit areas for each area;
Unused area start recording means for recording a pointer to the head unit area of the unused unit area managed for each of the plurality of divided areas;
An unused area end recording unit that records a pointer to the last unit area of the unused unit area managed for each of the plurality of divided areas.   2. The file management apparatus according to claim 1, wherein acquisition of a unit area at the time of data recording of a file is performed from a head unit area recorded in the unused area start recording means. A link means for linking to a unit area recorded in the file start recording means when deleting a file;
The file management apparatus according to claim 1, further comprising: a recording unit that records the unit area recorded in the file end recording unit in the unused area end recording unit. 2. A count unit that counts the number of accesses for each of the plurality of divided areas, and data recording at the time of file creation is performed from an area with a small number of accesses as a result of the counter unit. The file management apparatus according to any one of to 3.   5. The file according to claim 1, wherein the unused area linked by the unused area management unit is reconstructed so as to be linked to a nearby unused area. Management device. In a file management method for recording and managing file data on a recording medium composed of unit areas,
A data link step for linking and managing each unit area for recording file data;
A file start recording step for recording a pointer to a head unit area for recording data of each file;
A file end recording step for recording a pointer to the last unit area for recording data of each file;
An unused area management step of dividing the recording area of the recording medium into a plurality of areas and linking and managing unused unit areas for each area;
An unused area start recording step for recording a pointer to a head unit area of an unused unit area managed for each of the plurality of divided areas;
An unused area end recording step of recording a pointer to the last unit area of the unused unit area managed for each of the plurality of divided areas.   7. The file management method according to claim 6, wherein acquisition of a unit area at the time of file data recording is performed from a head unit area recorded in the unused area start recording step. A link step for linking to a unit area recorded in the file start recording step when deleting a file;
8. The file management method according to claim 6, further comprising: a recording step of recording the unit area recorded in the file end recording step in an unused area end recording step. A counting step for counting the number of accesses for each of the plurality of divided areas, and data recording at the time of file creation is performed from an area with a small number of accesses as a result of the counter step. The file management method of any one of -8.   The file according to any one of claims 6 to 9, wherein the unused area linked in the unused area management step is reconstructed so as to be linked to a nearby unused area. Management method.   A computer-readable recording medium on which a program for causing a computer to execute each step of the method according to claim 6 is recorded.   The program for making a computer perform each step of the method of Claim 6.

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