Patent ID: 7668874
Filing Date: 2010-02-23
Classification: G06F,Y10S

Abstract:
1. A computer system comprising: a primary host computer executing a primary database management system program; a primary storage subsystem coupled to the primary host computer; a secondary storage subsystem coupled to the primary storage subsystem; and a secondary host computer coupled to the secondary storage subsystem, which executes a secondary database management system program corresponding to the primary database management system program, wherein the primary storage subsystem, in response to a write request from the primary host computer, stores primary log information, primary database data, and primary status information, which are modified by the primary host computer based on the execution of the primary database management system program, the primary status information indicating a location of log information to be used at a time of switching transaction processing from the primary host computer to the secondary host computer, wherein, based on a synchronous remote copy from the primary storage subsystem, the secondary storage subsystem stores secondary log information which is a copy of the primary log information, wherein, based on an asynchronous remote copy from the primary storage subsystem, the secondary storage subsystem stores secondary database data and secondary status information which are copies of the primary database data and the primary status information, respectively, and wherein, upon a transaction processing being switched from the primary host computer to the secondary host computer, the secondary database management system program causes the secondary host computer to: (A) read the secondary status information stored in the secondary storage subsystem; (B) decide locations of the secondary log information, to be used to modify the secondary database data, based on the secondary status information; (C) read a part of the secondary log information indicated by the locations of the secondary log information; and (D) modify the secondary database data according to the part of the secondary log information so that modification of a completed transaction processed by the primary host computer is stored in the secondary database data.