Data backup method in a network storage system

• US 20040236984A1
• Filed: 08/15/2003
• Published: 11/25/2004
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamasaki, Yasuo
• Granted Patent: US 7,039,778 B2
• Time in Patent Office: Days
• US Class Current: 714/6
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 2201/855 Details of asynchronous mirroring using a journal to transfer not-yet-mirrored changes
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A data backup method in a network storage system in which mirroring is conducted between two disk units. The mirroring is delayed by accumulating update data in a cache for a predetermined period of time. When storing the update data in the cache, files are related to each other and information of file open and close is also stored. The update data is reflected in the mirrored disk using the file open and close information. As a result, the contents of the mirrored disk are delayed for a predetermined period of time from those of the primary disk, and all files are in other than the open state. Within a range of the period to store data in the cache, it is possible to restore data created at a point of time preceding a desired period of time. This recovers a user'"'"'s operation miss of erasing files by mistake.

Claims

1. An information processing system comprising:

a processor;

a memory;

a first disk unit;

a second disk unit;

first means for conducting synchronous mirroring from the first disk unit to the second disk unit;

second means for recording open and close information of files of the first disk unit in the memory; and

third means for using, in the asynchronous mirroring, the file open and close information.

2. An information processing system according to claim 1, wherein the memory stores the file open and close information, file update positions, and information regarding contents of update of files.

3. An information processing system according to claim 2 further comprising a function to handle only the open and close information in the memory without opening and closing files in the first disk unit.

4. An information processing system according to claim 2 further comprising a function to close a file in the first disk unit within a predetermined period of time after the file is opened.

5. An information processing system according to claim 2 further comprising a third disk unit onto which information stored in the memory is copied when a predetermined time lapses after the information is stored in the memory.

6. An information processing system according to claim 2, wherein the first means is an asynchronous mirroring section implemented by hardware.

7. An information processing system according to claim 2, wherein the asynchronous mirroring is conducted for each directory, not for each volume.

8. A method for use in a system including a processor, a memory, and a disk unit of producing backup of contents of the disk unit, comprising the steps of:

buffering update of the disk unit in the memory;

recording open and close information of files in the memory; and

using the file open and close information in controlling the buffering.

9. A backup method according to claim 8, wherein part of the disk unit is used as an area of the memory.

10. An information processing system, comprising:

a processor;

a first storage apparatus which can be accessed by the processor;

a second storage apparatus which can be accessed by the processor; and

a third storage apparatus,

the processor including a control unit for conducting a backup operation from the first storage apparatus to a second storage apparatus,

the third storage apparatus including update log of the first storage apparatus and information of file open and close in the first storage apparatus;

the control unit rewriting the second storage apparatus using the update log and the file open and close information of the first storage apparatus.

11. An information processing system according to claim 10, wherein the control unit prevent a write operation of a file, which is not closed after the file is opened, in the second storage apparatus using the update log of the first storage apparatus and information of time of the file open and close information of the first storage apparatus.

12. An information processing system according to claim 11, wherein the update log of the first storage apparatus includes a location to store information, information indicating contents of update, and time of update.