US Patent 7702865 Storage system and data migration method

A storage system and a data migration method that enable most suitable data migration with the correlation between data managed by particular applications being taken into account. The above storage system and data migration method are configured to collect operational information for each volume; respectively calculate a required volume performance level that is a level of performance required of the volume storing data that is a migration target, and an actual volume performance level that is a level of performance for each volume established in a storage apparatus, based on the collected information; and, in accordance with the calculated required volume performance level and each of the actual volume performance levels, when necessary, migrate the data that is a migration target to another volume having an actual volume performance level corresponding to the required volume performance level of the volume storing that data.