Patent ID: 7206832

Claim:
A computer system comprising: plural computers; and a storage system comprising plural interface control circuits coupled to said plural computers and plural logical units, wherein each of said plural logical units has an internal logical unit number and a virtual logical unit number; the internal logical unit numbers are used in said storage system for identifying said logical units and each of said logical units has a different internal logical unit number; the virtual logical unit numbers are used by said computers for identifying which of said logical units are accessible therefrom, and to those of said logical units which are accessible from each computer, virtual logical unit numbers beginning from 0 are assigned; said storage system is arranged to store information among the internal logical unit numbers, virtual logical unit numbers, and computers using the corresponding virtual logical unit numbers, and said storage system is arranged to receive an access request including a virtual logical unit number from a computer, convert the received virtual logical unit number to the corresponding internal logical unit number by referring to said information, and access the logical unit indicated by the internal logical unit number.