Patent ID: 8806126

Claim:
A storage apparatus, comprising: a control unit which is configured to manage a plurality of virtual volumes which are provided to a host, and a plurality of pool areas in which storage areas are assigned to the plurality of virtual volumes, wherein the virtual volumes comprise virtual disks which store data from the host and the virtual disks comprise a plurality of logical segments, wherein the pool areas comprise real volumes which actually store data from the host and the real volumes comprise a plurality of physical segments, wherein the control unit is configured to manage the logical segments in the virtual disks in association with the physical segments in the pool areas, for each of the plurality of pool areas, and wherein, if one virtual disk which is associated with one pool area is migrated to another pool area which differs from the one pool area, the control unit is configured to execute duplicate determination of data in the one virtual disk which is associated with the one pool area, execute the data duplicate determination between the one virtual disk which is associated with the one pool area and the other pool area on the basis of result of the duplicate determination, and migrate data which is stored in logical segments that the one virtual disk comprises, excluding duplicate data, to the other pool area.