Patent ID: 7716440

Claim:
A storage system comprising: a first disk array device that provides a first volume, wherein the first volume stores data transmitted from a host system; a second disk array device that provides a second volume, wherein the second volume is virtualized to a virtualized volume in said first disk array device; and a management terminal that manages said first disk array device, wherein said first disk array device comprises: a first management unit that manages volume information of the virtualized volume that was virtualized in said first disk array device by being mapped with said second volume; and a first transmission unit that transmits, based on an external operation, the volume information of said virtualized volume managed with said first management unit to said management terminal, wherein said management terminal comprises: a second management unit that manages the volume information of said virtualized volume transmitted from said first transmission unit, wherein the first management unit comprises a cache memory, wherein an online volume in which the host system will perform input/output processing of data is mapped to said virtualized volume, and an offline volume in which the host system will not perform the input/output processing of data is mapped to said virtualized volume, and wherein a capacity secured in the cache memory corresponds to the online volume in which the host system will perform input/output processing of data, and does not correspond to the off line volume in which the host system will not perform input/output processing of data, wherein said first disk array device further comprises: a migration unit that migrates data of said first volume to a second volume, wherein said first volume is set in a first physical device and said second volume is set in a second physical device, wherein said migration unit migrates the data of said first volume to said second volume upon lapse of a first period, wherein said first management unit manages the volume information of said virtualized volume corresponding to said second volume to which data was migrated with said migration unit, wherein said first transmission unit transmits the volume information of said virtualized volume to said management terminal upon lapse of a second period, and wherein said first disk array device: transmits the volume information of said virtualized volume corresponding to the second volume to the management terminal upon the lapse of the second period; deletes the transmitted volume information regarding the second volume from a storage area of the first management unit; and releases the capacity secured for the second volume in the cache memory.