Patent ID: 7120740

Claim:
A disk array unit, comprising: at least one disk array control unit connected to a host computer or disk drive; and an inter-unit cache memory switch (CM-SW) A connected to said disk array control unit and another disk array apparatus that is different from said disk array control unit; wherein said disk array control unit includes: an external device connection interface unit connected to said host computer or disk drive; an internal cache memory unit for storing data read/written from/to said disk drive or said another disk array apparatus; an internal shared memory unit for storing control information of the connection between said external device connection interface unit and said cache memory unit and management information of said disk drive; an internal cache memory switch B connected to said external device connection interface unit and said cache memory unit, as well as to said switch A; an internal shared memory switch C connected to said external device connection interface unit and said shared memory unit; and an internal protocol processing unit for processing commands addressed to an external volume control unit that stores volume information of said another disk array and said disk drive, wherein said switch A includes: an internal interface corresponding to an inter-unit cache memory switch (CM-SW) protocol A used for the communication in said disk array unit; and a protocol translation interface for translating data transmitted between said external device connection interface unit and said another disk array apparatus via the switch A from a FC or SCSI protocol B used in said another disk array apparatus into said protocol A, and wherein the disk array unit determines whether or not logical volumes of said another disk array apparatus are to be allocated to said host computer, if not, the disk array unit collects physical volume information of said disk array control unit from said internal shared memory unit, if yes, the disk array unit collects logical volume information of said another disk array apparatus therefrom.