Patent ID: 8131958

Claim:
A storage system comprising: a first storage device including a first data volume for storing data sent from a host computer and a first journal volume to which update data in the first data volume is written in a chronologically identifiable manner, a second storage device including a second data volume and a second journal volume that holds a replica of the first data volume and the first journal volume, and a management device managing the first storage device, wherein the first storage device comprises a recovery period management table including a start time of a recovery period, an end time of the recovery period, a merge flag which indicates whether or not the update data in the first journal volume in the recovery period is to be merged, and a replication flag which indicates whether or not the update data in the first journal volume in the recovery period is to be merged and transferred, wherein if the replication flag of a first recovery period is on, the first storage device sends the update data in the first journal volume written during the first recovery period to the second storage device, wherein if the replication flag of the first recovery period is off, the first storage device only sends the latest update data among the update data with the same write destination address which was written during the first recovery period, wherein if the merge flag of a second recovery period is on, the first storage device deletes the update data in the first journal volume except for the latest update data among the update data with the same write destination address which is written in the first journal volume during the second recovery period.