Patent ID: 7958391

Claim:
A storage system for providing data storage service to a host apparatus, comprising: a host interface unit configured to be connectable to the host apparatus; a disk interface unit configured to be connectable to a disk array unit having a volume storing data formed therein; a cache memory unit connected to the host interface unit and the disk interface unit, the cache memory unit configured to cache user data; a switch LSI connected respectively to the host interface unit, the disk interface unit, and the cache memory unit; a controller having a plurality of processors and connected to the switch LSI, wherein the switch LSI cuts off an I/O path with the controller based on an error signal output when an error occurs in one component in the controller; one or more signal lines configured to report an error, each of the signal lines providing an additional path to report the error, other than the I/O path; a non-volatile memory configured to store information indicating a failed component, wherein the stored information is referred to when determining whether the controller is operable, wherein the controller is operable if a component includes a plurality of elements and one or more of the elements are operable or if a component includes one element and the one element is operable; and wherein the controller, after performing error handling under control of one of the plurality of processors, commands the switch LSI to cancel the cutoff.