Apparatus and storage system for controlling acquisition of snapshot

• US 20050027749A1
• Filed: 02/02/2004
• Published: 02/03/2005
• Est. Priority Date: 07/29/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Tabuchi, Hideo, Ohno, Hiroshi, Shimada, Akinobu, Innan, Masataka
• Granted Patent: US 7,017,076 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 16/2308 Concurrency control transaction processing G06F9/466
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: G06F 2201/80 Database-specific techniques
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A DBMS performs a checkpoint process for maintaining consistency of data. A snapshot acquisition control program detects the checkpoint process externally to the DBMS and creates a snapshot in an external storage according to the timing of the checkpoint. Correspondence between checkpoints and snapshots is maintained in a CP-SH correspondence management table to make it possible to restore in a short time data at the time of an arbitrary checkpoint.

Claims

1. A snapshot acquisition controller for controlling acquisition of a snapshot cooperating with a computer system having a host computer on which a database management program (hereinafter referred to as DBMS) is operating, an external storage which stores data managed by said DBMS, and a snapshot function unit for acquiring a snapshot of data on said external storage upon receipt of a snapshot acquisition request, said DBMS intermittently executing a checkpoint process for temporarily storing update data for updating data on said external storage in a buffer and outputting all update data accumulated in said buffer to said external storage according to timing controlled by itself, comprising

checkpoint detection means which detects the execution of said checkpoint process that said DBMS intermittently executes according to timing controlled by itself;

and

snapshot acquisition request means which transmits said snapshot acquisition request to said snapshot function unit when the execution of said checkpoint is detected by said checkpoint detection means.

2. A snapshot acquisition controller according to claim 1, wherein

said checkpoint detection means detects the execution of said checkpoint process by monitoring an operation or information that the DBMS externally exhibits.

3. A snapshot acquisition controller according to claim 1, wherein

said checkpoint detection means detects the execution of said checkpoint process by monitoring an operation performed on said external storage by said DBMS or information output to said external storage by the same.

4. A snapshot acquisition controller according to claim 1, wherein

said checkpoint detection means detects the execution of said checkpoint process by monitoring an operation log that is a record of history of operations including said checkpoint process executed by said DBMS.

5. A snapshot acquisition controller according to claim 1, wherein

when said DBMS has a user interface for a manager and outputs information regarding said checkpoint process to said user interface for a manager, said checkpoint detection means detects the execution of said checkpoint process by monitoring information output by said DBMS to said user interface for a manager.

6. A snapshot acquisition controller according to claim 2, wherein

when said DBMS executes said checkpoint process at a first time interval, said checkpoint detection means performs a monitoring operation for detecting said checkpoint process at a second time interval shorter than said first time interval.

7. A snapshot acquisition controller according to claim 1, wherein

said snapshot acquisition request is transmitted without requesting said DBMS to staticize a database or to staticize a virtual database.

8. A snapshot acquisition controller according to claim 1, wherein further comprising

identification information storing means which stores checkpoint identification information for identifying a detected checkpoint process and snapshot identification information for identifying an acquired snapshot in association with each other when said snapshot is acquired as a result of detection of the execution of said checkpoint process.

9. A snapshot acquisition controller according to claim 8, wherein further comprising

snapshot restoration instructing means which, upon receipt of a snapshot recovery instruction including the specification of arbitrary checkpoint identification information, acquires snapshot identification information stored in association with the specified checkpoint identification information from said identification information storing means and which transmits a restoration request for a snapshot identified by the acquired snapshot identification information to said snapshot function unit or a predetermined functional unit having a snapshot restoring function.

12. A snapshot acquisition controller according to claim 3, wherein

when said DBMS executes said checkpoint process at a first time interval, said checkpoint detection means performs a monitoring operation for detecting said checkpoint process at a second time interval shorter than said first time interval.

13. A snapshot acquisition controller according to claim 4, wherein

when said DBMS executes said checkpoint process at a first time interval, said checkpoint detection means performs a monitoring operation for detecting said checkpoint process at a second time interval shorter than said first time interval.

14. A snapshot acquisition controller according to claim 5, wherein

when said DBMS executes said checkpoint process at a first time interval, said checkpoint detection means performs a monitoring operation for detecting said checkpoint process at a second time interval shorter than said first time interval.

10. A computer program for controlling acquisition of a snapshot used in conjunction with a computer system having a host computer on which a DBMS is operating, an external storage which stores data managed by said DBMS, and a snapshot function unit for acquiring a snapshot of data on said external storage upon receipt of a snapshot acquisition request, said DBMS intermittently executing a checkpoint process for temporarily storing update data for updating data on said external storage in a buffer and outputting all update data accumulated in said buffer to said external storage according to timing controlled by itself, the computer program causing a computer in or out of said computer system to execute the steps of:

detecting the execution of said checkpoint process that said DBMS intermittently executes according to timing controlled by itself, and

transmitting said snapshot acquisition request to said snapshot function unit when the execution of said checkpoint is detected at said step of detecting a checkpoint.

11. A storage system used in conjunction with a host computer on which a DBMS operates, comprising

an external storage which stores data in a database managed by said DBMS;

a snapshot function unit which acquires a snapshot of data on said external storage upon receipt of a snapshot acquisition request; and

a snapshot acquisition control unit for controlling the acquisition of said snapshot and in that when said DBMS is adapted to temporarily store update data for updating the data on said external storage in a buffer and to intermittently execute a checkpoint process for outputting all update data accumulated in said buffer to said external storage at timing controlled by itself, said snapshot acquisition control unit has;

checkpoint detecting means which detects the execution of said checkpoint process that the DBMS intermittently executes at timing controlled by itself; and

snapshot acquisition requesting means which transmits said snapshot acquisition request to said snapshot function means when the execution of said checkpoint is detected by said checkpoint detection means.