Patent ID: 7386598

Claim:
A computer system comprising: a first computer; a second computer; and a storage unit system; wherein said first computer, said second computer, and said storage unit system are connected to a network, and the first computer comprises a storage area network (SAN) server; wherein the first computer: offers a storage region possessed by the storage unit system as a virtual storage region to the second computer; receives a first instruction for the virtual storage region from the second computer; determines whether the storage unit system is capable of performing the first instruction; and either sends an instruction corresponding to the first instruction to the storage unit system if it is determined that the storage unit system can perform the first instruction, or itself performs the processing corresponding to the first instruction and provides the result of performing the first instruction to the storage unit system if it is determined that the storage unit system cannot perform the first instruction; wherein the computer system is adapted to respond to the first instruction relating to copying the virtual storage region such that when the virtual storage region is formed by coupling physical volumes having a first volume that can be copied by the storage unit system and a second volume that cannot be copied by the storage unit system, the data in the first volume is copied by the storage unit system and the data in the second volume is copied by the first computer and, after both sets of data have been copied, the first computer couples the data copied by the first volume and the data copied by the first computer from the second volume and completes the copying of the virtual storage region as a copy of the data copied from the first and second volumes.