US 7,925,633 B2Granted

Disaster recovery system suitable for database system

AssigneeHitachi, Ltd.

InventorsYoshio Suzuki, Nobuo Kawamura, Kota Yamaguchi, Shinji Fujiwara, Satoru Watanabe, Masaru Kitsuregawa

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Abstract

To reduce operational and management costs during normal operations while recovering a database without loss and maintaining on-line performance on a site. A first system includes a primary storage system (103) that stores a DB (107) and a main computer (100) that executes a primary DBMS (101), which provides a DB. A second system includes a secondary (113) that receives from the primary storage system (103) a copy of a log, which shows update differences of the DB (107), and stores a secondary DBMS (117), and a subset (500) that recovers the secondary DB (117) according to the log that is copied from the primary storage system (103). When a failure occurs in the first system, the first system is switched to the second system. A second computer (110) that executes a second DBMS (111) is added to the second system, and the secondary DB (117) that is recovered or is being recovered in the subset (500) is taken over to the second computer (110).

Claims16

Dependent claims

A data recovery and takeover method in a disaster recovery system including a primary site having a first storage system storing a first database and a first server provided with a first database management system (DBMS) managing the first database, and a secondary site, located remotely from the primary site, having a second storage system storing a second database which duplicates the first database and a recovery module, the method comprising:

copying a log indicating an update difference in said first database into a log file formed in the second storage system by a remote copy via an inter storage network which connects the first storage system and the second storage system, when the update difference is generated in said first database;
when the log indicating the update difference is copied by the remote copy, reading out the copy of the log from the log file formed in the second storage system by the recovery module and applying the log on said second database by the recovery module, in a log applying process which is kept alive until the second site receives a failover instruction;
upon a time when the second site receives the failover instruction, interrupting the log applying operation of the data recovery process and marking a log record indicating a start of an oldest uncommitted transaction at that time as a check point;
according to the failover instruction, starting in the secondary site a second server which is provided with a second DBMS which is to take over the first DBMS;
informing the second server of execution condition of the interrupted data recovery process including information of the check point from the recovery module,
taking over by the second DBMS provided in the second server a data recovery of the second database.

3 more elements

copying a log indicating an update difference in said first database into a log file formed in the second storage system by a remote copy via an inter storage network which connects the first storage system and the second storage system, when the update difference is generated in said first database;
when the log indicating the update difference is copied by the remote copy, reading out the copy of the log from the log file formed in the second storage system by the recovery module, and applying the log on said second database by the recovery module, in a log applying process which is kept alive until the second site receives a failover instruction;
when the second site receives the failover instruction, continuing the log applying operation until a completion up to an end of the logs copied in said log file, and undoing logs concerned in uncommitted transactions by the recovery module;
according to the failover instruction, starting in the secondary site a second server which is provided with a second DBMS which is to take over the first DBMS;
and
after confirming a completion of the log applying operation and undoing the logs concerned in the uncommitted transactions, informing the second server of a completion of the data recovery process from the recovery module.

3 more elements

copying a log indicating an update difference in said first database into a log file formed in the second storage system by a remote copy via an inter storage network which connects the first storage system and the second storage system, when the update difference is generated in said first database;
when the log indicating the update different is copied by the remote copy, reading out the copy of the log from the log file and buffering the log;
analyzing buffered logs to find committed transactions;
applying the logs concerned in the committed transactions on said second database by the data recovery process;
when the second site receives the failover instruction, continuing the log applying operation until a completion up to an end of logs copies in said log file by said recovery module;
according to the failover instruction, starting in the secondary site a second server which is provided with a second DBMS which is to take over the first DBMS;
and
after confirming a completion of the log applying operation, informing the second server of a completion of the data recovery process from the recovery module.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/989,398Filed 17 Nov 2004
Priority: JP 2004-17943317 Jun 2004
Published: US 2005/0283504 A122 Dec 2005
Granted: 12 Apr 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G06F 11/2028
Failover techniques: eliminating a faulty processor or activating a spare
G06F 11/2025
Failover techniques: using centralised failover control functionality
G06F 11/2097
Using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements: maintaining the standby controller/processing…
G06F
Computing and data processing