Patent ID: 7711908

Claim:
A virtualization storage system comprising: a plurality of storage systems; and a virtualization layer for virtualizing the plurality of storage systems logically into a single storage resource provided to a host computer, wherein each of the plurality of storage systems includes the same first correspondence information regarding correspondence relationships between commands from the host computer and functions of the plurality of storage systems and the same second correspondence information regarding correspondence relationships between the functions and the storage systems that have the functions, and wherein, when the virtualization storage system receives a command from the host computer, the virtualization storage system sends the command to one of the storage systems, and said one of the storage systems determines whether it is in possession of the function corresponding to the command by referring to the first correspondence information and the second correspondence information stored in said one of said storage systems, and, if said one of said storage systems does not possess the function corresponding to the command, said one of the storage systems retrieves another one of the storage systems in possession of the function corresponding to the command from the plurality of storage systems by referring to the first correspondence information and the second correspondence information stored in said one of said storage systems, and transfers the command to said another one storage system in possession of the function corresponding to the command.