Patent ID: 7529964

Claim:
The disaster recovery system executing a backup operation while arranging a first system and a second system in remote locations, wherein the first system comprises: a first calculating machine executing a first DBMS providing the first database; a first storage for storing a log to which an update difference of the first database is output at each of transactions, and the first database; a command adding unit for adding a command to the log; and a remote copy unit transferring the log to the second system, wherein the second system comprises: a second storage for storing a log received from the first system and a second database; and a database recovering unit for recovering the second database on the basis of the log received from the first system, and wherein the database recovering unit comprises: a command extracting section for extracting the command included in the log; and a command executing section for executing the extracted command, wherein the command adding unit adds to the log a snapshot generating command for instructing a snapshot generation as an instruction output to the second system, wherein the second storage has a mirror set capable of changing a plurality of volumes between a pair state and a split state, wherein the command executing section instructs the second storage to generate the snapshot in the case that the extracted command is constituted by a snapshot generating command, and wherein the second storage stores the mirror set in the second database under a split state after writing the second database in a plurality of volumes so as to synchronize by setting the mirror set to a pair state, on the basis of the snapshot generating instruction.