Patent ID: 8850255

Claim:
A storage system comprising: a storage device which stores data; and control units each of which controls an operation for accessing said storage device, each of said control units including: a relay unit which relays access to said storage device, an access controller which selects one of a first path passing through the relay unit belonging to said control unit and a second path passing through another relay unit belonging to another control unit and accesses said storage device through the selected path when said control unit and said another control unit are in a normal operational state, and an operational-state controller which determines whether or not said another relay unit belonging to said another control unit is usable when the operational-state controller detects occurrence of an abnormality in said another control unit, and makes said another control unit transition to a partially-operational state when said another relay unit belonging to said another control unit is determined to be usable, wherein when said another control unit is in the partially-operational state, a portion of said another control unit including another access controller is not in operation and the access controller in said control unit continues to select one of the first path and the second path and access said storage device through the selected path.