Patent ID: 6412078
Filing Date: 2002-06-25
Classification: G06F

Abstract:
An external storage subsystem to be connected to a host system, comprising:a plurality of controllers having a plurality of input/output (I/O) ports and unique identifiers (IDs) as addresses of corresponding I/O ports; and a group of storage devices shared with said controllers, wherein said controllers are connected to said host system via an interface cable, and upon occurrence of a failure in a failed controller, said failed controller recognizes failure therein and enters a wait state without executing control operation thereof for at least a period of time while a normal controller performs a transfer process transferring control information of said failed controller to said normal controller and an address addition process adding the port address of said failed controller to the port address of said normal controller, wherein said normal controller monitors a state of said interface cable to start the transfer and address addition processes, wherein said failed controller erases the port address thereof after said normal controller finishes the transfer and address addition processes, and wherein said normal controller responds to a subsequent I/O request issued from said host system after said normal controller receives the port address of said failed controller and the port address of said failed controller has been erased.