Patent ID: 8843715

Claim:
A storage system comprising: a first control unit; at least one first storage device; at least one first port to be coupled to a computer; at least one second port to be coupled to an external storage system comprising at least one second storage device and a second control unit providing an external logical volume by the at least one second storage device; wherein the first control unit is configured to: manage a first volume, wherein a write data to the first volume is stored in a storage area in the at least one first storage device in the storage system, manage a second volume, wherein a write data to the second volume is stored in a storage area, which is mapped to the second volume, of the at least one second storage device which provides the external logical volume, create a copy pair between the first volume and the second volume which are selected from a list of volumes provided by the first control unit with information of either the at least one first storage device or the at least one second storage device as a storage device in which the data of each of the volumes is stored, and operate a copy function between the first volume and the second volume to copy data between the at least one first storage device and the at least one second storage device.