Patent ID: 7240188

Claim:
A storage system, comprising: a shared memory, storage devices and control units having a plurality of circuit boards that carry out control for storing data in the storage devices, wherein each of the circuit boards comprises a CPU; an I/O processor for controlling inputs and outputs between the CPU and the storage devices; a memory which the CPU and the I/O processor use for jobs; a nonvolatile memory which holds firmware; and a network control section that provides services concerning the data inputs and outputs to an information processing apparatus connected via a first network by an OS which operates on the CPU, a cluster of fail-over processing is formed with said circuit boards including at least one targeted circuit board for an update of firmware, each of the control units has a service moving function for taking over the services between OSs on the circuit boards in the cluster, the storage system executes, at the time of updating the firmware for said targeted circuit board for said update of firmware, processings including: service move processing to move service being provided by the OS of said targeted circuit board to the OS of another one of the circuit boards in the cluster by the service moving function; firmware update processing for updating the firmware on the nonvolatile memory of said targeted circuit board to a new firmware by the use of a firmware update program and a new firmware image for the targeted circuit board which is in a non-service providing state after the move of the service, and the I/O processor of said each circuit boards monitors a state of the respective CPU, stores OS state information, that represents operating and installation conditions for the respective OS, on the shared memory, and decides whether to shut down the respective OS and whether to move service between the circuit boards by referring to the OS state information on the shared memory.