Patent ID: 8224782

Claim:
A computerized storage system comprising: a. a client host computer; b. a source first tier storage system operatively coupled to the client host computer, the source first tier storage system having at least one source first tier storage device having a plurality of source first tier chunks arranged into a source chunk pool and a source storage controller; c. a second tier storage system operatively coupled to the source first tier storage system, the second tier storage system having at least one second tier storage device having a plurality of second tier chunks arranged into the chunk pool of the source first tier storage system, wherein the source storage controller is operable to allocate source first tier chunks or second tier chunks from the source chunk pool to a source thin provisioned volume accessible by the host computer upon a receipt of a write command directed to the source thin provisioned volume from the host computer; and d. a target first tier storage system operatively coupled to the client host computer and to the second tier storage system, the target first tier storage system having at least one target first tier storage device having a plurality of target first tier chunks arranged into a target chunk pool and a target storage controller operable to establish a target thin provisioning volume, wherein upon migration of data from the source thin provisioning volume to the target thin provisioning volume the source first tier chunks of the source thin provisioning volume are copied to the target first tier chunks of the target thin provisioning volume and the second tier chunks are re-mapped from source second tier chunks of the source thin provisioning volume to target second tier chunks of the target thin provisioning volume without copying data in the second tier chunks.