Patent ID: 8799600

Claim:
A computer system comprising: a storage system including a plurality of physical storage drives and a controller providing a plurality of volumes, where the controller uses a plurality of storage regions provided by the plurality of physical storage drives as a plurality of logical storage regions of the plurality of volumes; and a management computer configured to: (A) receive information for specifying a source volume among the plurality of volumes; (B) receive a migration condition; (C) after step (B), if a candidate volume satisfying the migration condition among the plurality of volumes excluding the source volume exists, extract the candidate volume; (D) if at least one candidate volume is extracted according to step (C), instruct the storage system to execute a data migration from the source volume to the candidate volume; and (E) if no candidate volume is extracted according to step (C): (E1) extract a portion of the plurality of physical storage drives satisfying the migration condition which was already received in step (B); (E2) instruct the storage system to execute a creation of a volume, using empty regions of the storage regions provided by the extracted portion of the plurality of physical storage drives as logical storage regions; and (E3) instruct the storage system to execute a data migration from the source volume to the created volume, wherein the migration condition includes a disk type or a RAID level.