Patent ID: 8463981

Claim:
A storage apparatus, comprising: a storage device storing data; a controller configured to control data reading and writing of the storage device; a volume virtualization unit configured to virtualize the storage device and provide a higher-level device with the virtualized storage device as a virtual storage capacity; an administration table administrating which location in the storage device a piece of data in the virtual storage capacity is stored; an access frequency administration table administrating an access frequency to the piece of data stored in the storage device: and a deduplication unit configured to perform deduplication by integrating pieces of data redundantly allocated in the storage device, wherein the deduplication unit is configured to acquire access frequencies to respective pieces of data redundantly allocated in the storage device from the access frequency administration table, obtain a sum thereof, and, if the sum is less than a prescribed threshold, perform the deduplication by integrating pieces of data into any one thereof and update the storage location information of the piece of data in the storage device before the deduplication that is held by the administration table to storage location information of the piece of data in the storage device after the deduplication, wherein the deduplication unit, if the access frequency to the piece of data equals to or is more than the prescribed threshold after pieces of data are integrated in the deduplication, is configured to duplicate the piece of data subjected to the deduplication and pieces of data are redundantly allocated again, and update the storage location information of the piece of data in the storage device alter the deduplication that is held by the administration table to storage location information in the storage device after the duplication.