Patent ID: 7801933

Claim:
A storage system, comprising: a plurality of disk devices including a first type disk device and a second type disks device, the first type storage disk device having a different reliability attribute and/or performance attribute from the second type storage disk device; and a control unit managing a virtual volume, a plurality of first type disk areas and a plurality of second type disk areas, wherein the virtual volume is accessed from an external device by specifying a logical unit number, the plurality of first type disk areas correspond to the first type disk device, and the plurality of second type disk areas correspond to the second type disk device; wherein the control unit allocates at least one of the plurality of first type disk areas to a first portion of the virtual volume and stores data to be stored to the first portion of the virtual volume to the at least one of the plurality of first type disk areas, and allocates at least one of the plurality of second type disk areas to a second portion of the virtual volume to and stores data to be stored to the second portion of the virtual volume to the at least one of the plurality of second type disk areas.