Patent ID: 8429462

Claim:
A storage system for accessing storage devices according to data access requests from a requesting device, the storage system comprising: a plurality of storage devices; at least one controller that controls access to said plurality of storage devices; a pair of loops, in which information circulates in a single direction, to exchange information between said controller and said plurality of storage devices; and a plurality of switch circuits, provided in each of said pair of loops, each of said plurality of switch circuits comprising: a plurality of port switches that each connects and bypasses each of said plurality of storage devices to and from said loop and creates a loopback path from corresponding storage device of said plurality of storage devices to the corresponding storage device; and a switch controller that is connected to said loop and is connected parallel to said plurality of port switches and connects and bypasses each of plurality of port switches to and from the loop, wherein when said at least one controller detects a loop anomaly while accessing said storage devices, said at least one controller issues an instruction to restore said loop, and wherein the switch controller, in response to said instruction from said controller, bypasses all said plurality of port switches, creates said loopback path in all of said plurality of port switches connected to corresponding said storage devices after all of said port switches have been bypassed by parallel operating said plurality of port switches to diagnose said storage devices, and wherein said storage devices execute an initialization process and send a signal to said port switch in response to creation of the loopback path in the port switch, and the switch controller monitors the signals in said port switches from each of said storage devices, judges that a storage device that did not send the signal is anomalous, and disconnects said storage device judged to be anomalous from said loop.