JPH06110759A - File system - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the storage area required for file duplication. [Constitution] Under the control of the file system 11, the copy source and copy destination files share the same data management unit in the secondary recording device 12. Therefore, the secondary recording device 12 needs only a data management unit for one file. Also, when changing one of such files,
Only the data management unit that needs to be changed is newly prepared on the side of the file to be changed, and different data management units are used for the copy source file and the copy destination file, so that the file can be changed with fewer data blocks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file system of a computer system.

[0002]

2. Description of the Related Art Conventionally, in a file system of a computer, data in each file unit is stored in a different data management unit in a secondary storage device. Here, the data management unit is a unit in which the file system manages the storage area of the secondary storage device, and its size is an appropriate size in terms of access speed and effective use of the storage area. Be present. An example is shown in FIG.
In this figure, the data of file 1 is contained in data management units 0, 1, 3, 6, 7. Further, the data of the file 2 is stored in 4, 5, 8 and the data of the file 3 is stored in the data management unit 9, 10, 11, 12. In the secondary storage device, it becomes as shown in FIG.
As described above, in the conventional file system, different data management units in the secondary storage device are associated with each file.

Here, 01, 02, and 03 in FIG. 1A are file identification data. This is a data structure in the OS prepared for each file when the OS creates a new file. The file identification data describes the number of the data management unit of the secondary storage device in which the data of the file is stored, and the OS knows the data management unit number corresponding to the file by referring to the file identification data. Is able to. In FIG. 18A, a data management unit in which file data is contained is shown connected by a line.

Generally, in a computer system,
Frequent duplication of files. For example, an important file is duplicated and used as a backup file so that the original file can be erased or changed accidentally due to an operation error. In this case, although the file exists in the system as two different entities, the data content in the file is exactly the same. An example is shown in FIG. The data of file 1 is in data management units 0, 2, 3, and 4, and the data of file 2 is in data management unit 1,
6, 7, and 8. Although file 1 and file 2 are separate files, they are the same as data, and the data management units 0 and 1, 2, 6, 3, 7, 4, and 8 in the secondary storage device contain the same data. There is. As a result, the data is redundantly stored in the secondary storage device, which is wasteful. For example, as shown in FIG. 6B, the original file has a size of 4 data blocks, so that when one copy is made, four disk areas of four data management units are newly used.

[0005]

As described above, in the conventional file system, as a result of file duplication (copy), a space equal to the size of the original file is newly added for the file to be duplicated. It is stored in the secondary storage device. As a result, there is a drawback that double storage space is used for two files having exactly the same data.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a file system which requires less space for file duplication.

[0007]

According to the present invention, in a computer system in which data is stored as a file for each purpose on a secondary storage device, each data management unit of the secondary storage device has its data management unit. A file number managing means for managing the number of files associated with each other, a means for copying the files so that the copy source file and the copy destination file share the data management unit in the secondary storage device, and A means for detecting whether or not the data management unit that needs to be changed is a data management unit shared by a plurality of files according to the management content of the file number management means, and a data management unit that needs to be changed. Is shared by a plurality of files, an empty data management unit is newly prepared and the changed data is written. When that is not shared Airu to that and means for changing the data of the data management unit and the first feature.

In this file system, as a result of file duplication, two different files having the same contents as seen by the user remain. However, since the copy source and copy destination files share the same data management unit in the secondary recording device, only one file data management unit is required. That is, the capacity of the secondary recording device can be effectively used as compared with the conventional method. Moreover, when changing one of such files, a new data management unit is prepared for the file side that changes only the data management unit that needs to be changed, and different data management units are used for the copy source and copy destination files. , Files can be modified with fewer data blocks.

Further, according to the present invention, the data is stored as a file on the secondary storage device for each purpose, and at the time of file duplication, a new area is secured on the secondary storage device for the duplication destination file. In a computer system that duplicates a file by writing the data of a duplication source file there, means for storing a set of data management units having the same data generated by the duplication of the file, and managing time information regarding access to each file And second means for reallocating the data management unit at a predetermined timing so that the data management unit having the same data is shared between the files based on the time information. .

In this file system, for example, by reallocating files that have not been accessed for a certain period of time so that the files share a data management unit, the area occupied by the less accessed files on the secondary recording device is saved. can do.

Further, according to the information on the used area of the secondary storage device, it is possible to reallocate the data management unit so that the files having the data management unit containing the same data are shared with each other. it can. In this file system, for example, when the unused area in the secondary recording device becomes small, the data management unit is shared between the files, so that the remaining small used area can be effectively used.

Further, in order to prevent the data management unit from being irregularly allocated as a result of such re-allocation and thus deteriorating the access efficiency, a file sharing the data management unit with other files should be allocated. When I access it,
By re-allocating the data management unit so that the data management unit is not shared and the data arrangement is optimized at that time, the access speed to such a file can be improved.

[0013]

FIG. 1 shows a file system according to a first embodiment of the present invention. In this example, the file system 11
Accesses the magnetic disk 12 as a secondary storage device. A reference counter 14 corresponding to each data management unit 13 is stored in the disk 12 as data in the disk. It is taken into the main memory when the file system 11 starts up, and while the system is operating,
The reference counter 14 in the main memory is accessed so that the data is written back into the disk 12 again when the system stops. In this way, the file system 1
Since 1 does not need to access the disk 12 every time the reference counter 14 is accessed, the overhead is small.

When creating a new file and writing data, the file system 11 performs the processing shown in FIG. First, the file system 11 creates file identification data 15 for a file in the file system (step S1). At this point, no data management unit is assigned to the file. When data is subsequently written to this file, the file system 11 secures one empty disk data management unit for storing the data (step S2), and associates (assigns) it with the file identification data. , The value of the reference counter 14 corresponding to the data management unit is set to 1 (steps S3 and S4). That is, the value of the reference counter 14 indicates that this data management unit is associated with one file. Then, the file data is written (step S5). Such processing is repeated until all the data is written (step S6).

Next, a process for copying a file will be described. Note that the file is generally copied by the user using an OS command. For example, the command name is'cop
When y'is specified, copy 'copy source file name''copy destination file name' is executed, and a copy destination file having the same content as the copy source file is created with a new file name.

The processing of the file system 11 at this time is shown in FIG. As a result, the copy destination file shares the data management unit of the copy source file.

Therefore, first, file identification data for the copy destination file is created in the file system (step S11). Then, the following processing is performed for each data management unit of the copy source file.

1) The value of the reference counter corresponding to the data management unit is incremented by 1 (step S12).

2) The data management unit is registered in the file identification data of the copy destination file (step S13).

By repeating this processing (step S14), each data management unit is referenced by both the copy source file and the copy destination file, and the reference counter of the data management unit is associated with the copy destination file. What you have done is reflected.

Next, the file change will be described.
The processing of the file system 11 at this time is shown in FIG.

When changing the data in the file,
Regarding the data management unit that needs to be changed, it is checked whether or not the reference count is 1 (step S21), and only in the case of 1, the data is changed to that data management unit (step S22). When the reference counter is 1, there is no file other than this file that shares this data management unit, so the data management unit may be changed. On the other hand, when the value of the reference counter is larger than 1, there are files other than this file that share the data management unit. In this case, if this data management unit is changed, the data in other files will also be changed. Therefore, assign a new data management unit and write the changed data to those data management units. To do.

Therefore, when the reference count is larger than 1, first, the value of the reference counter of the data management unit is decremented by 1 (step S23), and the data management unit is separated from the file identification data (step S2).
4) Prepare new empty data management units (step S25), set the reference counters corresponding to them to 1 (step S26), and register the number of the data management unit in the file identification data (step S27). The changed data is written (step S28). These processes are repeated until there is no data management unit that needs to be changed (step S29).

Next, the file deletion will be described.
The processing of the file system 11 in this case is shown in FIG.

Also here, if the value of the reference counter of the data management unit of the file to be deleted is 1 and it is 1, the file is released as it is because it is not shared with other files. However, with respect to the data management unit whose reference counter has a value larger than 1, since the other files share it, the reference counter is reduced by one. As a processing procedure, the reference counts of all the data management units associated with the file to be deleted are decremented by 1 (step S3
1), it is determined whether or not the result is 0 (step S
32). For the data management unit that resulted in 0,
Since it is a data management unit that is not referred to by another file, it is released to be an empty data management unit (step S3
3) After that, the file identification data is deleted (step S35).

FIG. 6 shows a result of writing the data by newly creating the file 1. Next, FIG. 7 shows a state in which a file 2 which is a duplicate file of the file 1 is created. After that, a state in which a part of the data of the file 1 (data management unit 6, 7) is changed is shown in FIG. Finally,
The state when the file 1 is deleted is shown in FIG.

In FIG. 6, file 1 is block No. 0, No, No. 1, No. 3, No. 6, N of the disk 12.
The data are stored in a distributed manner in five data management units of o and 7, and the reference counter values at this time are all 1. When a file 2 which is a duplicate file of the file 1 is created, as shown in FIG. 7, the physical data management unit of the disk 12 is not changed and only the reference counter value of each data management unit is changed to 2. To be done. File 1 in this state
When the contents of the data management units 6 and 7 are updated, the update result is stored in the data management units 13 and 2, for example, as shown in FIG. In this case, blocks No. 13, No. 2 are added to the reference counter table. Then, the reference counter values corresponding to the data management units 6 and 7 are changed to 1. If file 1 is deleted, data management unit 13, which is not shared with file 2,
2 is deleted, and the reference counter values of the data management units 0, 1, 3, 6, 7 become 1.

Next, a second embodiment according to the present invention will be described. In this example, when a file is duplicated, a set of data management units containing the same data is held as management data in the file system 11. This data structure will be called a "same data management unit table".

The file system 11 reflects the influence of these processes in this "same data management unit table" when a file is copied, data in the file is changed or deleted. The file system 11 checks the access time information of each file at regular intervals, and the process shown in FIG. 10 for all data management units of files that have not been accessed for a period longer than a predetermined time (time T). Do.

Here, it is assumed that the file system 11 can obtain the file identification data of the file to which the data management unit is allocated from the number of the data management unit. For this, for example, the management information of each data management unit may have information for discriminating the file identification data of the file to which the data management unit is assigned.

First, one data management unit of the file F to be processed is selected and designated as Bt (step S4).
1). Then, refer to the "same data management table",
It is checked whether or not there is another data management unit Bs containing the same data as Bt (step S42). The process branches depending on whether or not the data management unit Bs exists (step S4).
3) If it exists, the processes of steps S44 to S47 are executed. In step S44, the data management unit B
One of s is selected and becomes Bsi. Step S4
In step 5, it is determined whether the file Fsi to which the data management unit Bsi is assigned has not been accessed for a period longer than the time T (step S45). In step S45, if the data management unit Bsi is not accessed for a period longer than the time T, the data management unit Bsi is released, and instead, the data management unit Bt is assigned to the file Fsi. The processes of steps S44 to S47 are performed for all the data management units Bs (step S47).

FIG. 11 shows an example. Here, it is assumed that the data management units 2, 3, 4, and 5 are assigned to the file 1. The same data management unit table at this time is shown on the right side of the same figure. In this figure, the numbers of data management units containing the same data are shown in the same column. At this point, these data management units are not shared with other files.

Next, this file is duplicated to obtain file 2
FIG. 12 shows the state when the above. Data management units 11, 12, 13, and 14 are newly assigned to the file 2. Here, since the data management units 2 and 11, 3 and 12, 4 and 13, 5 and 14 contain the same data, the “same data management unit table” is as shown on the right side of FIG. Become. At this point, 8 data management units are used in 2 files. After that, the data management unit 4 of the file 1 was changed. As a result, data management units 4 and 1
Different data will be stored in No. 3, as shown in FIG.

Furthermore, as a copy of file 2, file 3
FIG. 14 shows the result of making the data and then changing the data of the data management unit 13 of the file 2. Suppose that sufficient (> T) time has passed and files 1, 2, and 3 have not been accessed during that time. At this time, when the file system 11 performs the above-described processing of FIG. 10, the data management unit (2, 1
1,28), (3,12,29), (5,14,31)
Have the same data, the result is as shown in FIG. In this example, three files share the three data management units 2, 3, and 5.

In the conventional case, 12 data management units are required, but in this example, half the number is required.
The time T is set by the user in advance.

Next, a third embodiment of the present invention will be described.
In the third embodiment, the file system 11 periodically obtains information about the used area of the secondary recording device 12 to check its size (ratio), and determine the predetermined value (U [%]). 10) when it is larger than
Perform the processing shown in. The other points are the same as those in the second embodiment.

For example, if U = 90%, the processing of FIG. 10 is performed for all files when 90% or more of the secondary recording device 12 is used and there is no room.
As a result, the data management unit containing the same data is shared by a plurality of files, the storage area of the secondary recording device 12 can be saved, and the unused storage area can be increased to some extent. become. The value of U is set by the user in advance.

The information on the used area can be easily checked by using, for example, the number of data management units registered in the data management table.

Next explained is the fourth embodiment of the invention.
Here, it is assumed that the present invention is applied to the second embodiment or the third embodiment.

FIG. 16 shows the result of the second or third embodiment,
The file system 11 when an access occurs to a file sharing a data management unit with another file
Is a process performed by. First, the file system 11
The file to be accessed is checked to see if the data management unit is shared by other files (step S51). When all the data management units are not shared, they are accessed as they are. If there is at least one data management unit shared with another file, a new storage area for that file is secured in the secondary recording device 12 (step S52), and the data of this file is copied (step S52). (S53), the original data management unit is separated from the file identification data of this file (step S54). After that, the file to which a new data management unit is assigned is accessed (step S5).
5).

FIG. 17 shows the file 3 in the state of FIG.
The result when accessing is shown. In the state of FIG. 15, the file 3 shares the data management units 2, 3 and 5 with the other two files. In this case, the file system 11 reserves new data management units 23, 24, 25, 26 for the file 3 and copies the data of the data management units 2, 3, 30, 5 there. Then, from the file identification data of file 3, data management unit 2,
3, 3, 5 are separated and 23, 24, 25, 26 are related (assigned). After that, especially with respect to the data management unit 30, since there are no files allocated as a result, the data management unit 30 is released.

Generally, in a storage device such as a disk, the file system is designed so that the seek of the head is reduced and the sequential access is efficiently performed in consideration of the disk rotation speed and the access timing. Place the file data. For example, the data management unit of the file 1 in FIG. 11 before sharing the data management unit with other files is 2, 3, 4, 5
These are generally assigned as a result of considering the above points. On the other hand, the file generated by the second or third embodiment is a data management unit that is reassigned so that the data management unit is shared with another file. No optimization is done.

For example, the data management unit of the file 3 in FIG. 15 is 2, 3, 30 and 5, which is different from the optimum arrangement (2, 3, 4, 5) when it is assigned to the file 1.
Access efficiency of such files may deteriorate.

This problem can be solved by applying the fourth embodiment. That is, when accessing a file that shares a data storage unit with another file, the data of the file may be arranged again in an optimal arrangement. In this example, the data management units 23, 24,
25 and 26. As a result, high-speed access can be realized.

As described above, according to the first embodiment, the operation of copying the original file is performed as follows:
The data corresponding to two different files of the created backup file correspond to the same data management unit group inside the disk. As a result, with the conventional method, two files occupy a double storage area, but a single file storage area is sufficient.
Therefore, it becomes possible to effectively use the secondary storage device.
This is especially useful for making backup files of large files. In addition, when the file or the copy source file is changed after the duplicate file is created, a new data management unit is assigned to the file only for the changed data management unit. Therefore, according to the present invention, even when a large number of files are created by gradually changing a certain file, the number of data management units is smaller than that of the conventional method, and the storage area of the secondary storage device is effectively used. be able to.

Further, according to the second embodiment, for example, files that have not been accessed for a certain period of time (that is, files with low access frequency) can be managed so as to share a data management unit containing the same data. As a result, it is possible to reduce the proportion of files that are not frequently accessed, and it is possible to effectively use the storage area of the secondary storage device.

Further, according to the third embodiment, for example, by allocating the data management unit so that the data management unit containing the same data is shared between the files when the free area of the secondary storage device becomes small. , Free space increases,
It is possible to prevent the secondary storage area from filling up to some extent.

Further, according to the fourth embodiment, when a file sharing a data management unit with another file is accessed, the data unit is not shared again and the data arrangement is optimized at that time. By reallocating the data management unit so that the access speed to the file generated as a result of applying the second or third embodiment can be improved.

[0049]

As described above, according to the present invention, it is possible to further reduce the storage area of the secondary storage device required for duplicating a file.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a file system according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation in the first embodiment.

FIG. 3 is a flowchart for explaining the operation of the first embodiment.

FIG. 4 is a flowchart illustrating an operation in the first embodiment.

FIG. 5 is a flowchart for explaining the operation of the first embodiment.

FIG. 6 is a diagram showing a first state when files are created, copied, changed, and deleted in order in the file system according to the first embodiment.

FIG. 7 is a diagram showing a second state when files are created, copied, changed, and deleted in order in the file system according to the first embodiment.

FIG. 8 is a diagram showing a third state in which file generation, duplication, modification, and deletion are sequentially performed in the file system according to the first embodiment.

FIG. 9 is a diagram showing a fourth state in which file generation, duplication, modification, and deletion are sequentially performed in the file system according to the first embodiment.

FIG. 10 is a flowchart illustrating the operation of the file system according to the second embodiment of the present invention.

FIG. 11 is a diagram showing a first state when a file is duplicated, changed, and reassigned in file management units to a file that has not been accessed for a certain period in the second embodiment.

FIG. 12 is a diagram showing a second state when file duplication, modification, and reassignment of a file management unit to a file that has not been accessed for a certain period in the second embodiment.

FIG. 13 is a diagram showing a third state when file duplication, modification, and reassignment of a file management unit to a file that has not been accessed for a certain period in the second embodiment.

FIG. 14 is a diagram showing a fourth state of file duplication, modification, and reassignment of a file management unit to a file that has not been accessed for a certain period in the second embodiment.

FIG. 15 is a diagram showing a fifth state in the case of duplicating and changing a file and reallocating a file management unit to a file that has not been accessed for a certain period in the second embodiment.

FIG. 16 is a flowchart for explaining the operation in the fourth embodiment of the present invention.

FIG. 17 is a diagram showing the appearance of a processing result file in the fourth embodiment.

FIG. 18 is a diagram showing a relationship between a file in a conventional file system and a data management unit in the secondary recording device.

FIG. 19 is a diagram showing a result of file duplication in a conventional file system.

[Explanation of symbols]

11 ... File system, 12 ... Secondary storage device, 13 ...
File data management unit, 14 ... Reference counter table, 15 ... File identification data table.

Claims (4)

[Claims] 1. A computer system for storing data as a file for each purpose on a secondary storage device, for each data management unit of the secondary storage device, managing the number of files associated with that data management unit. A file number managing means, a means for copying the file so that the copy source file and the copy destination file share the data management unit in the secondary storage device, and the file number managing means for changing the data in the file. A method for detecting whether or not the data management unit that needs to be changed is a data management unit that is shared by multiple files according to the management content of When a new empty data management unit is newly prepared and the changed data is written, and the data management unit is not shared by a plurality of files, File system characterized by comprising a means for changing the data over data management unit. 2. Data is stored as a file for each purpose on a secondary storage device, and at the time of file duplication, a new area is reserved on the secondary storage device for a duplication destination file, and duplication is performed there. In a computer system that duplicates a file by writing the data of the original file, means for storing a set of data management units having the same data generated by the file duplication, means for managing time information regarding access to each file, A file system, comprising means for reallocating a data management unit at a predetermined timing so that a data management unit having the same data is shared between files based on the time information. 3. The reallocation means comprises means for obtaining information on the used area of the secondary storage device, and based on the information of the means, for files having a data management unit containing the same data. 3. The file system according to claim 2, wherein the data management units are reallocated so that the data management units are shared. 4. The data reallocating means manages data so that the file does not share a data management unit with another file when an access occurs to a file sharing a data management unit with another file. The file system according to claim 2 or 3, wherein units are reassigned.