Patent ID: 8719496

Claim:
A storage apparatus which is connected via a network to a host apparatus that issues data input/output (I/O) requests, comprising: a microprocessor package configured to access a logical volume to which the microprocessor package has ownership rights, wherein: the microprocessor package includes a plurality of microprocessors and any of the plurality of microprocessors can access the logical volume; and the logical volume includes one or more storage areas provided by a plurality of storage devices; a local memory in the microprocessor package, the local memory configured to: store a counter value indicating a number of I/O requests to and from a logical volume; and lock the local memory when a counter value is to be incremented; wherein each microprocessor in the microprocessor package is configured to: store, if there is one I/O request from the host apparatus, an I/O request range of the one I/O request in the local memory, wherein the I/O request range includes a start position address and an end position address of the logical volume which is a target of the I/O request; acquire the counter value of the logical volume which is the target of the one I/O request; store the acquired counter value in the local memory; if the counter value of the logical volume associated with the one I/O request is greater than the counter value of the logical volume associated with another I/O request, compare the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request; if, as a result of comparing the I/O request range of the one I/O request stored in the local memory and the I/O request range of the other I/O request, there is no overlap between the I/O request ranges, execute the one I/O request processing; and if there is an overlap between the I/O request ranges, place the processing of the one I/O request on standby.