Patent ID: 7194675

Claim:
A backup method used in a backup system in which a primary system and a secondary system are connected via a first communication link, the primary system including a primary database management system (DBMS) and a primary storage device, the secondary system including a secondary DBMS and a secondary storage device, the primary and the secondary storage devices being connected via a second communication link, the primary storage device including a primary database (DB) and a plurality of primary logical log volumes each storing a plurality of log records, the secondary storage device including a secondary DB which is a backup volume of the primary DB, and a plurality of secondary logical log volumes each storing a plurality of log records, the backup method for duplicating log records from the primary system to the secondary system, comprising: (a) forming a plurality of logical log volume pairs, with each logical log volume pair including a primary logical log volume of the primary logical log volumes and a secondary logical log volume of the secondary logical log volumes; (b) providing, on a side of the primary system, a management table for storing states of the logical log volume pairs; (c) setting one of the logical log volume pairs to an active state, while setting other logical log volume pairs to a standby state, and storing the states thus set to the management table; (d) storing, on the side of the primary system, a log record in a primary logical log volume of the active-state log volume pair; (e) sending the log record thus stored from the primary storage device to the secondary storage device via the second communication link until the primary logical log volume of the active-state log volume pair is fulfilled with log records; (f) receiving, on a side of the secondary system, the log record sent from the primary storage device, storing the log record thus received in the secondary logical log volume of the active-state log volume pair, and performing an update operation to the secondary DB based on the log records stored in the secondary logical log volume of the active-state log volume pair; (g) when the primary logical log volume of the active-state log volume pair is fulfilled, setting in a ring buffer manner, on the side of the primary system, another one of the logical log volume pairs to an active state, while setting the prior active-state log volume pair in which the primary logical log volume is fulfilled to a standby state, and storing the states thus set to the management table to update the management table; and (h) releasing the logical log volume pair thus fulfilled, and executing the operations (d) to (g).