Patent ID: 7831792

Claim:
A computer system having one or more host computers, a storage system to store data used by the host computers and a storage management server to manage a storing of the data in the storage system, all these being interconnected through a network; wherein the storage system comprises: one or more storage devices to store the data used by the host computers; and one or more controllers to control the storage devices, the controllers storing the data in the storage devices by volumes, the volume being a physical or logical unit for data storage; wherein the storage management server comprises: a memory unit to store physical configuration information including at least information on a physical configuration of the controllers or storage devices of the storage system; and a processing unit to manage the storage devices of the storage system by the volumes; wherein, when two or more volumes of data in the storage system are parallelly migrated to the same number of other volumes, the parallel migration operation is executed by referencing the physical configuration information stored in the memory unit, evaluating physical conflicts of the controllers or storage devices in the storage system for each volume and, based on the evaluation, selecting volumes with few conflicts, and wherein the processing unit of the storage management server references the physical configuration information stored in the memory unit, calculates a maximum parallel processing number, namely the maximum number of the volumes that can be parallelly migrated and for which physical conflicts of the controllers or storage devices in the storage system are less than a predetermined level, and executes the parallel migration operation on the maximum parallel processing number of volumes.