JPH02257229A - File recovery system for computer system - Google Patents

Abstract

PURPOSE:To shorten the processing time of the file recovery by executing the backward read of a journal file, and also, managing the presence of page updating with one bit unit, while reading a backup file in order from a first record, and restoring the file with a single write as for the same page. CONSTITUTION:At the time of restoring a user file 10 to the latest state by the generation of a fault of a disk device, etc., a page input part 14 executes the backward read of a journal file 30 extending from the latest record of time to the oldest record. Subsequently, at the time of reaching the end point of the journal file 30, the read of a page image is executed from a backup file 20, as well, a write page flag for showing by one bit unit whether a page managing part 42 executes the write of an object page or not is set to a page management file 43, and also, informs whether a write experience exists or not. In the case of a page having no write experience, a page output part 44 writes it to the user file 10, and in the case of a page having a write experience, this write is inhibited. In such a manner, the processing time of the file recovery can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a computer system. The present invention relates to a file recovery method, and more particularly to a file recovery method for restoring user files while reading journal files backwards.

〔overview〕

The present invention is based on the file recovery method of computer systems that updates user files in case of a disk device failure, reads the journal file backwards from the latest time record to the oldest record, and then reads the backup file from the first record. By reading sequentially from page to page, managing whether or not a page has been updated in 1-bit units, and recovering the file by writing once to the same page, the time required to return the journal file to the starting point is saved and the file recovery process is It is designed to save time.

[Conventional technology]

Conventionally, this type of file recovery method first copies a backup file to a user file, then overwrites the page image many times from the oldest record to the latest record in the journal file to recover. Alternatively, a method has been adopted in which the same pages are sorted in chronological order to reduce the number of times they are written to the user file.

[Problems to be solved by the invention] The conventional file recovery method described above requires time to write and sort the same page of the user file many times, which makes the recovery process difficult. It had the disadvantage of being time consuming.

The present invention aims to eliminate such drawbacks and provides a method that can shorten file recovery processing time.

[Means for solving problems]

The present invention periodically copies a user file to a backup file in case of a disk device failure, and updates the user file while accumulating this updated image in a journal file when updating a certain page of the user file. In a file recovery method for a computer system equipped with a recovery program means, a page management file for holding a write page flag is provided, and the recovery program means is provided with the above-mentioned information when restoring the user file to the latest state due to the occurrence of a disk device failure. A page input unit that reads a journal file backwards from the latest record to the oldest record, and reads a page image from the backup file when the end point of the journal file is reached, and a page input unit that reads the page image from the backup file, and writes out the target page. The page management section sets a write page flag indicating whether or not the page has been written in 1-pit units in the page management file and notifies whether or not the page has been written, and if the page has not been written before, it is written to the user file and the The present invention is characterized by comprising a page output section that prohibits writing if it is a certain page.

[Effect]

When restoring a user file to the latest state due to a disk device failure, etc., the page input section reads the journal file backwards from the latest record to the oldest record, and when the end point of the journal file is reached. The page image is also read from the backup file, and the page management section sets an export page flag that indicates in 1-bit units whether or not the page has been exported to the page management file, and notifies whether or not there has been any export experience, and outputs the page. If the page has never been written before, it will be written to the user file, and if the page has been written before, this writing will be prohibited.

As a result, the time required to return the journal file to the oldest point and the time required for the sorting process is not wasted, and the processing time for file recovery can be shortened. This is particularly effective when a magnetic tape recording device is used as a journal file.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In the embodiment of the present invention, the user file 10 is periodically copied to the backup file 20 in case of a disk device failure, and when a certain page of the user file 10 is updated, this updated image is stored in the journal file 30 while the user The recovery program means 40 is provided with a recovery program means 40 for updating the file 10, and is further provided with a page management file 43 for holding a write page flag. A page input unit 41 that reads the journal file 30 backwards from the latest record to the oldest record, and also reads page images from the backup file 20 when the end point of the journal file 30 is reached, and the target page. The page management unit 4 sets a write page flag in the page management file 43 that indicates whether or not writing has been performed in 1-pit units, and also notifies whether or not there is writing experience.
2, and a page output unit 44 that writes to the user file 10 if the page has not been written before, and prohibits writing of the page if the page has been written.

FIG. 2 is a diagram showing the record format in the backup file 20 according to the embodiment of the present invention, in which file names and page images are arranged in order of page numbers.

FIG. 3 is a diagram showing the record format in the journal file 30 according to the embodiment of the present invention, in which a rule code is composed of a file name, a page number, and an updated page image.

The page manual section 41 in the recovery program 40 positions the end of the journal file 30 and reads the code backwards. For example, user file 100 page number 100
If so, the page output section 44 checks whether it is a record of the user file 10 and calls the page management section 42 . The page management section 42 has a page management file 43.
When checking whether the 100th bit (write page flag) in the page management file 43 is in the on state and finding that it is in the off state, the page management unit 42 writes the 1st bit in the page management file 43.
After turning on the 00th bit, the page output section 44
Notify that the page needs to be exported.

The page output unit 44 writes this page image to the user file IO and passes control to the page input unit 41.

While performing similar operations for other records, if the page input unit 41 reads page number 100 of the user file 100 again, the page output unit 44
calls the page management section 42, and the page management section 42 inspects the page management file 43 and finds that the 100th bit is already in the on state. Therefore, the page management department 42
notifies the page output unit 44 that there is no need to write the page. The page output unit 44 passes control to the page input unit 41 without doing anything.

If the above operations are repeated and there are no more records in the journal file 30, the page input unit 41 reads the backup file 20 from the first record in order and passes it to the page output unit 44 in the same record format as the format read from the journal file 30. Add the file name and page number to the above record and output it to the page output section 4.
Pass it to 4. The subsequent operations are performed in the same manner as when processing records read from the journal file 30.

By repeatedly performing the above operations until the end point of the backup file 20, the user file 10 can be restored with one write operation for the same page.

Next, an outline of the operation will be explained using the schematic flow shown in FIG.

The page input section 41 reads the journal file 30 backwards (
Step 200) is performed to determine the end of the journal file 30 (step 210). If the journal file 30 is in an unfinished state, the page output unit 44 calls the page management unit 42. The page management unit 42 inspects the page management file 43, notifies the page output unit 44 of the on/off state of the write page flag, and sets the write page flag (step 220).

The page output unit 44 determines the write page flag (step 230), and if it is on, performs reverse reading of the journal file 30 (step 200).

If it is off, write the page image (step 240) and then reverse read the journal file 30 (step 240).
Step 200) is performed.

Determination of end of journal file 30 (step 210)
If the journal file 30 is in the completed state, the page input unit 41 reads the backup file 20 (step 250) and determines whether the backup file 20 is completed (step 260). If the backup file 20 is in an unfinished state, the page output unit 44 calls the page management unit 42. The page management unit 42 inspects the page management file 43 and turns on/off the export page flag.
The page output unit 44 is notified of the off state and a write page flag is set (step 270).

The page output unit 44 determines the write page flag (step 280), and if it is on, reads the backup file 20 (step 250). If it is off, export the page image Step 2
After performing step 90), the backup file 20 is read (step 250).

Determination of end of backup file 20 (step 260
), if the backup file 20 is in the completed state, the file recovery process ends.

〔Effect of the invention〕

As explained above, according to the present invention, the journal file is read backwards from the latest record to the oldest record, and the backup file is read in order from the first record to check whether or not a page has been updated in 1-bit units. By managing and restoring a file by writing it once to the same page, it is possible to shorten the processing time for file recovery.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a diagram showing the record format of a backup file according to an embodiment of the present invention. FIG. 3 is a diagram showing the record format of the journal file according to the embodiment of the present invention. FIG. 4 is a flowchart showing an outline of the operation of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 10...Five-the file, 20...Backup file, 30...Journal file, 40...Recovery program means, 41...Page input section, 42
...Page management department, 43...Page management file,
44...Page output section.

Claims (1)

[Scope of Claims] 1. In case of a disk device failure, a user file is periodically copied to a backup file, and when a certain page of the user file is updated, this updated image is stored in a journal file while the user In a file recovery method for a computer system equipped with a recovery program means for updating files, a page management file is provided for holding a write page flag, and the recovery program means is configured to restore the user file to the latest state due to the occurrence of a disk device failure. a page input unit that reads the journal file backwards from the latest time record to the oldest record when the journal file is read, and reads a page image from the backup file when the end point of the journal file is reached; A page management unit that sets an exported page flag indicating whether or not a page has been exported in 1-bit units in the page management file and notifies whether or not there is any experience of exporting, and if the page has no experience of exporting, it is exported to the user file. A file recovery method for a computer system, comprising: a page output unit that prohibits writing if the page has been previously written.