Patent ID: 9201607
Filing Date: 2015-12-01
Classification: G06F

Abstract:
1. A computer system, comprising: a storage device including a plurality of storage areas; a virtual volume to which access from a host system are permitted; a plurality of logical volumes, each including a storage area, of the plurality of storage areas, and each being a pool volume of a pool; and a controller which is configured to control allocation of a storage area from the plurality of pool volumes in the pool to the virtual volume on a storage area unit basis for storing data of a write request, wherein the controller is configured to: receive a request for a pool volume deletion; specify at least one of the pool volumes which is to be deleted; migrate data stored in the pool volume which is to be deleted to other pool volumes so as to balance a usage rate of each of the remaining pool volumes in the pool; and change an allocation of a storage area, in the pool volume to be deleted, to the virtual volume, to an allocation of a storage area of the pool volume storing the migrated data to the virtual volume, wherein the usage rate for each pool volume is a ratio of the storage areas allocated to the virtual volume among total storage areas of the pool volume which can be allocated to the virtual volume.