Patent ID: 8074048

Claim:
A storage device for storing data in accordance with a request from a server, the storage device comprising: a memory for storing data in a plurality of logical volumes, the logical volumes being a plurality of areas assigned logically; a controller for controlling an access to data stored in the logical volume in accordance with a process comprising the steps of: generating mapping information indicative of a correspondence between logical volume information and recognition information, the logical volume information being indicative of the logical volumes in the storage unit, the recognition information being referred to by the server to recognize the logical volume; generating a pseudo logical volume and pseudo logical volume information associated with the pseudo logical volume, the pseudo logical volume being another of the logical volumes; and upon receipt of a command for canceling an assignment of one of the logical volumes to the corresponding recognition information, modifying the mapping information so that recognition information that has been indicative of said one of the logical volumes becomes indicative of the pseudo logical volume information associated with the pseudo logical volume.