Patent ID: 8677094

Claim:
A storage system, comprising: a first storage apparatus including a plurality of first storage devices, a first virtual volume, and a first controller; and a second storage apparatus including a plurality of second storage devices, a second virtual volume, and a second controller, wherein the second virtual volume includes a plurality of allocated second storage areas and the second virtual volume is currently being used by the storage system; wherein the first controller is configured to: provide the first virtual volume to a computer; dynamically allocate, to the first virtual volume, one of a plurality of first storage areas in the plurality of first storage devices for storing data from the computer; set a copy pair between the first virtual volume and the second virtual volume for copying the data, in units of storage areas, from the first storage apparatus to the second storage apparatus, wherein the second virtual volume is no longer currently being used by the storage system; determine whether the data is stored, in units of storage areas, in the first storage area allocated to the first virtual volume; send the data stored in the allocated first storage area from the first storage apparatus to the second storage apparatus in units of storage areas; and issue a release instruction to the second controller to release at least one of the plurality of allocated second storage areas from the second virtual volume when the copy pair is formed; and wherein the second controller is configured to: release the at least one of the plurality of allocated second storage areas from the second virtual volume in response to receiving the release instruction from the first controller; dynamically allocate the at least one released second storage area to the second virtual volume for storing another data received from the first storage apparatus; and issue a copy commencement instruction to the first controller; and wherein the first controller is further configured to execute the copying in response to receiving the copy commencement instruction from the second controller.