Patent ID: 7356658

Claim:
A storage system comprising: a disk device which comprises: an original volume for storing data which is read/written by a host; a copy volume for storing a copy of the original volume at a predetermined timing; and a snapshot volume for storing a snapshot data which is a snapshot of the original volume; and a storage control unit which comprises: a management unit for managing the storage control unit; a channel I/F that is connected to the host; and a device I/F that is connected to the disk device, wherein the management unit: copies data of the original volume to the copy volume at a predetermined timing; stores the snapshot data in the snapshot volume corresponding to a write request to the original volume; manages a generation of the stored snapshot according to predetermined copy volume blocks and snapshot volume blocks, and manages a generation of the copy volume; and reads data from the snapshot volume and/or the copy volume when a read request to a volume of a generation different from that of the original volume is received from the host.