JPS6286426A - Data base backup system - Google Patents

Abstract

PURPOSE:To attain the earlier restoration of a data base by providing a backup processing section including a means updating the same image as that of an active data base independently of the on-line data base processing from a journal extraction means to a backup disc device. CONSTITUTION:In updating a data base of a disc device 13, an image before and after the update of record is stored in an on-line journal 14 and the journal is transferred to a backup processing section 15 at the same time. Then only the image journal after the update of data base required to update of the backup disc deice 17 is extracted by an extracting means 18 and a disc update means 19 and a disc control device 16 update the backup disc device 17 thereby generating the active data base image in on-line. Thus, the effect of the processing performance onto the on-line data base processing is minimized as the backup system of the data base and the earlier restoration of the data base is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Minute Hand] The present invention relates to a database backup method that maintains independence from online database system processing so as to quickly recover from a database failure in an online database system.

[Conventional technology]

Conventional backup methods for quick recovery from database device failures include a dual write method in the operating system, where when a program writes to a disk device, it writes to both the current and backup disk devices, and a disk controller device that writes to both the current and backup disk devices. A dual write method is known in which data is written to subordinate current and backup disk devices.

[Problems that the invention attempts to solve] In the backup method that performs dual writing in the conventional operating system described above, input and output to both the current and backup disk devices cannot be treated with the same level of priority. Nowadays, disk devices and disk controller devices must be configured with consideration given to the maximum load, including dual writing.

This is because an online database system, which tends to have a large fluctuation in disk input/output load, has a redundant configuration and the 9-by-7 ohmance has dropped. Alternatively, if this consideration is not taken, there is a drawback that a high disk input/output load may cause a delay in disk input/output access time, which may lead to a decrease in the performance of the online system.

On the other hand, the importance of databases in existing online database systems is high, and shortening failure recovery time has become a major issue. The response (performance) of this online system is one of the most important factors, and it cannot be tolerated that performance deteriorates due to database failure recovery.

SUMMARY OF THE INVENTION An object of the present invention is to provide a database backup method for an online system that solves the problems of the prior art and enables early database recovery.

[Means for solving problems]

The configuration of the database backup method of the present invention includes: a backup disk device; a disk control device that controls input/output of this disk device; and a journal transfer that takes over the online journal output for recovery when updating the database of the online database system. means: a journal extraction means for extracting an image journal after database update from the output of the transfer means; and a disk update means for updating the same image as the current database from the journal extraction means to the backup disk device, which is independent of online database processing. It is characterized by having a backup processing unit including a

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing an outline of an embodiment of the present invention. In the figure, 11 is an online processing unit, 12, 16 is a disk control device, 13, 17 is a disk device for the current database and backup, and 14 is an online journal that stores images before and after record updates on magnetic tape etc. for recovery purposes. , 15 is a database backup processing section including journal extracting means 18 and disk updating means 19. When the online database processing unit 11 updates the database in the disk device 13 (8), it stores images before and after the record update in the online journal 14 (B), but at the same time, does this journal need to be transferred to the backup processing unit 15? , extracting means 1 only for the image journal after the database update necessary for updating the backup disk device 17
8), update the data to the disk device itl 7' using the disk update means 19 and the disk control device 16, and create a current database image online.

The processing of the database backup processing unit 15 is normally placed at a lower priority level in terms of processing and input/output issuance than the processing of the online database processing unit 11.

By taking over (transferring) the online journal 14, the backup processing unit 15 can be placed in a separate computer system from the online database processing.

〔Effect of the invention〕

As described above, the present invention makes it possible to realize a database backup method that minimizes the impact on processing performance on online database processing.

In addition, by using the database vari-up method of the present invention, it is especially effective for systems with important online databases or systems that place emphasis on performance, and is useful for early database recovery and for selecting a medium for taking over online journal images. Yes, it will become possible to develop a remote location bavku-up system as a response to risk dispersion.

[Brief explanation of drawings]

FIG. 1 is a block diagram 61 containing one embodiment of the present invention. 11...Online processing section, 12.16...
... Disk control device, 13... Current disk device, 14... Online journal, 15... Database backup processing unit, 17. Old... Backup disk device. , 18...
. . . Journal extraction means, 19 . . . Disk update means.

Claims (1)

[Claims] A backup disk device; A disk control device that controls the input/output of this disk device; A journal transfer means that takes over the online journal that is output for recovery when updating the database of the online database system; A database is transferred from the output of this transfer means. The backup processing unit includes a journal extracting means for extracting an updated image journal, and a disk updating means for updating the backup disk device with the same image as the current database independent of online database processing from the journal extracting means. A database backup method featuring: