JP2738245B2 - File recovery system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art When a failure occurs in a recording apparatus and files on the apparatus are restored by the latest save tape, the state of these files is returned to the state at the time of save. The operation of returning the file state to the save point using the save tape is called restoration. On the other hand, if the journal function is specified for the journal that records on a journal tape each time it is updated, the journal status that contains the updated image after the evacuation point is used to determine the file status. Can be further brought to the current state. Recovering files based on such a journal tape is called "roll forward".

Conventionally, in the case of a file created on the assumption that the file is restored by the roll forward, a file size changing operation of reducing the file size has been prohibited. This is because the necessary files are deleted due to the file reduction, so that when the journal tape is used, it cannot be recovered as inappropriate.

[0004]

Further, if an increase in the file size, that is, file expansion, is allowed, it is necessary to predict in advance the data increase and secure a sufficient file area. For this reason, there is a disadvantage that the use efficiency of the secondary storage medium is low.

[0005] Further, when the file needs to be expanded due to an increase in data which has been used for many years, the file must be recreated once, which is not convenient for the user. Was.

[0006]

SUMMARY OF THE INVENTION A file recovery system according to the present invention includes a file which exists on a secondary storage medium and is created on the assumption that it is recovered by roll forward, a file size at the time of a file failure, and a current file size. File size adjusting means for comparing the file size and changing to the file size at the time of occurrence of a failure, and file changing means for expanding or reducing, that is, changing the file called from the file size adjusting means. The file changing means includes at least one of the file expanding means and the file reducing means in one embodiment of the present invention.

[0007]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention is:
For processing at the time of updating a file, a file 7 created on the premise of restoration by roll forward, a process of referring to, updating, expanding and reducing this file 7, a file management for receiving various requests from the process 1 to the file 7 Unit 2, a journal record creation and output unit 8 for creating and outputting each of the extended, reduced, and updated journal records in accordance with an instruction from the file management unit 2, and records journal records created and output by the journal record creation and output unit 8 A journal tape group 9 to be updated and a save tape 10 for saving a file image in advance before updating the file 7 are included.

The file management unit 2 includes a file expansion unit 3 for expanding the file 7 in response to an expansion processing request for the file 7 from the process 1 and a file 7 in response to a reduction processing request for the file 7 from the process 1. Processing means 4 for reducing the size of the file 7 in response to an update processing request for the file 7 from the process 1
And a file reference means 6 for performing a reference process of the file 7 in response to a reference process request for the file 7 from the process 1.

Next, one embodiment of the present invention includes a roll-forward means 11 for restoring the file 7 using a journal record at the time of failure of the file 7 and a file 7 to be restored for the purpose of file restoration.

The roll forward means 11, which is one of the features of the present invention, comprises: a journal record extracting means 12 for extracting a journal record relating to the file 7 from the journal tape group 9;
Sorting means 13 for rearranging the journal records extracted in step 1 in the order of journal record type, update position and chronological order, comparing the file size at the time of file failure with the current file size, and expanding or reducing the size to return to the file size at the time of failure. File size adjusting means 14 for determining which of the file sizes is required; file expanding means 15 which is called from file size adjusting means 14 when file 7 needs to be expanded and which actually expands file 7; file 7 needs to be reduced File reducing means 16 which is called from the file size adjusting means 14 when the file size occurs and which actually reduces the file 7, and the file updating means 1 which updates the file 7 in accordance with the updated journal record
7 inclusive.

Next, before describing the operation of one embodiment of the present invention, the format of each record will be described in detail with reference to the drawings.

Referring to FIG. 2, the extended journal record has a record type 2 indicating the type of the journal record.
01, a file ID 202 for uniquely identifying the file 7 in the system, an expansion size 211, and a file size 212 of the file 7 after expansion.

Referring to FIG. 3, the reduced journal record has a record type 2 indicating the type of the journal record.
01, a file ID 202 for uniquely identifying the file 7 in the system, a reduced size 221 indicating the reduced size of the file 7, and a file size 222 indicating the size of the file 7 after the reduction.

Referring to FIG. 4, the update journal record has a record type 2 indicating the type of the journal record.
01, a file ID 202 for uniquely identifying the file 7 in the system, an updated image 232 indicating an updated image, and relative position information 231 of the updated image 232 in the file 7.

In this embodiment, the extended journal record shown in FIG. 2 and the reduced journal record shown in FIG. 3 are collectively called a changed journal record.

Next, the operation of the embodiment of the present invention, in particular, the operation at the time of updating a file with reference to FIG. 5 and the operation at the time of file recovery with reference to FIG. 6 will be described in detail.

First, it is assumed that the image of the file 7 is saved on the save tape 10 in advance. Note that the file saving / restoring operation does not particularly relate to the present invention, and thus details are omitted.

Referring to FIG. 5, when updating a file,
The following processes are respectively performed in response to various requests from the process 1 to the file 7 [310, 320, 330,
340].

When a reference request is given to the file 7 from the process 1 [310], the file reference means 6 in the file management unit 2 is called, the file 7 is read, and the image of the file 7 is returned to the process 1. [3
11].

When an extension request is issued from the process 1 to the file 7 [320], the file extension means 3 in the file management unit 2 is called. The file extension means 3 first expands the file [321], and then calls the journal record creation / output means 8 to create an extended journal record and output it to the journal tape group 9 [322].

When a reduction request is issued from the process 1 to the file 7 [320], the file reduction means 4 in the file management unit 2 is called. The file reduction means 4 first reduces the file [331], and then calls the journal record creation / output means 8 to create a reduced journal record and output it to the journal tape group 9 [332].

The order of the creation / output of the change journal record and the actual change processing is opposite to the order of the creation / output of the update journal record because the size information in the journal record is actually changed when the file size change fails. This is to avoid conflict with the file size.

When an update request is given to the file 7 from the process 1, the file update means 5 in the file management unit 2 is called. The file update means 5 first calls the journal record creation / output means 8 to create an updated journal record and causes the journal tape group 9 to output the updated journal record [341]. Thereafter, the file updating means 5 updates the file 7 [342].

When the file 7 is damaged due to a device failure or the like, the file 7 is restored as follows.

First, the file 7 is restored on another device by the save tape 10.

Next, roll forward processing is performed as follows.

Referring to FIGS. 1 and 6, the roll forward means 11 calls the journal extracting means 12 in itself, and extracts the journal record for the file 7 from the journal tape group 9 [401].

The roll-forward means 11 adds a sort key to the extracted journal records, and the sort means 13 sorts the journal records in ascending key order [402].

Referring to FIGS. 1, 4 and 6, the following five keys are used to sort the journal records. The first key is the file ID 202, the second key is the journal record type 201, the third key is the relative position information 231 of the updated journal image in the file, the fourth key
The key is a relative tape number in the journal tape group 9, and the fifth key is a relative record number in the journal tape. Here, since the fourth and fifth keys do not exist in the journal record, the journal record extracting means 12 adds them to each journal record. The fourth and fifth keys are used to arrange journal records in chronological order.

Assume that the journal record type 201 as the second key has a change journal record of 1 and an update journal record of 2.

It is also assumed that the value of the third key of the change journal record is 0.

After the sorting is completed, the roll forward means 11
Reads the journal records [403] and [404] while storing only one change journal record until an updated journal record is found in order to obtain the change journal record immediately before the failure.
When an update journal is found, the file size of the file 7 immediately before the occurrence of the failure is obtained from the expanded file size 212 or the reduced file size 222 in the saved change journal [406].

The file size adjusting means 14 compares the obtained file size with the file size of the current file 7, and if the current file size is smaller, expands the file 7 using the file expanding means 15 [ 40
7, and 408], on the contrary, if large, the file 7 is reduced using the file reducing means 16 [409, 4]
10].

Thereafter, the file updating means 17 performs a roll forward using each updated journal record.
At this time, the in-file relative position information 231 of the update image in the journal record is compared with the current file size of the file 7, and when a failure occurs, an update journal record for a non-existent file position is found. The roll-forward process is terminated at the end of the process [412 and 41].
1].

The reason why the roll-forward processing is terminated when an updated journal record corresponding to a non-existent file position is found when a failure occurs is to eliminate waste caused by updating the journal record of a portion truncated by the reduction processing.

The file size can be freely changed even if the file is created on the premise of the roll-forward recovery.

[0038]

According to the present invention, it is possible to freely change the file size of a file created on the premise of roll-forward recovery in the same manner as a normal file, thereby enabling the secondary storage medium to be effectively used. There is an effect that utilization can be achieved and user convenience can be improved.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a diagram showing a format of an extended journal record.

FIG. 3 is a diagram showing a format of a reduced journal record.

FIG. 4 is a diagram showing a format of an updated journal record.

FIG. 5 is a diagram for explaining a processing operation at the time of updating a file;

FIG. 6 is a diagram for explaining a processing operation at the time of file recovery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Process 2 File management part 3 File expansion means 4 File reduction means 5 File update means 6 File reference means 7 File 8 Journal record creation / output means 9 Journal tape group 10 Save tape 11 Roll forward means 12 Journal record extraction means 13 Sorting means 14 file size adjusting means 15 file expanding means 16 file reducing means 17 file updating means

Claims (1)

(57) [Claims] 1. A file that exists on a secondary storage medium and is created on the assumption that it is restored by roll forward, a save tape that saves a file image of the file, and a journal record for the file is created. Create journal records to output to journal tapes
An output unit, a file expansion unit that expands the file in response to an expansion processing request for the file, creates an extended journal record by the journal record creation / output unit, and outputs the extended journal record to the journal tape group; In response to a request for reduction processing, the file is reduced, the reduced journal record is created by the journal record creation / output means, and output to the journal tape group. Restoring the file based on the stored file image, reading the extended journal record or the reduced journal record corresponding to the file immediately before the failure from the journal tape group, and reading the extended journal record or the reduced journal Roll forward means for obtaining the size of the file after expansion or reduction from the record; comparing the size of the file after expansion or reduction obtained by the roll forward means with the size of the file at the time of restoration, and restoring If the size of the file at the time is smaller, the file is expanded by the file expanding means, and if the size of the file at the time of restoration is larger, the file reducing means reduces the file by the file reducing means. A file recovery system characterized by comprising: