<p>A plurality of storage area groups which are obtained by classifying a plurality of storage areas provided from a plurality of storage devices in accordance with attributes of the storage areas are managed. In response to a write request to at least one address included in a plurality of addresses in a logical volume, a plurality of logical volumes to which at least one storage area included in the plurality of storage areas is assigned are provided. In accordance with an access situation of the at least one address in the logical volume, data which is written to the at least one address in response to the write request is shifted from the at least one storage area included in one of the plurality of storage area groups to at least one storage area in another storage area group included in the plurality of storage area groups.</p>
