Patent ID: 7412628

Claim:
A storage system which accesses a plurality of storage devices in response to data access requests from a request device, comprising: a plurality of storage devices; at least one controller which controls said plurality of storage devices; a pair of loops, in which information circulates in a single direction, for exchanging information among said controller and said plurality of storage devices; a plurality of first switches, provided in one of said loops, to connect one of said pair of loops to said plurality of storage devices; a plurality of second switches, provided in another one of said loops, to connect said another one of said pair of loops to said plurality of storage devices; a first device control unit, connected by a first path to said controller and connected by a second path to said storage devices, and which operates said plurality of first switches; and a second device control unit, connected by a third path to said controller and connected by a fourth path to said storage devices, and which operates said plurality of second switches, said first, second, third and fourth paths comprising physical paths separated from said pair of loops, wherein said controller has a first disconnect mode for issuing a disconnect instruction to any one of said first and second device control units via said first path or said third path; and a second disconnect mode for issuing a disconnect instruction to any one of said first and second device control units via any one of said pair of loops, said storage device, and said second path or said fourth path, and wherein said controller executes one of said first disconnect mode and said second disconnect mode when detecting a fault of the storage device from a response when accessing said storage device through said one of said loops, and executes another of said first disconnect mode and said second disconnect mode when detecting a faulty disconnect of said faulty storage device by executing said one of said first disconnect mode and said second disconnect mode.