Patent ID: 7966448

Claim:
A storage apparatus for providing a host computer with a data write area where write data is written, the write area being a first dynamically allocated storage area volume that can be dynamically expanded by allocating a logical volume to the first dynamically allocated storage area volume, the apparatus comprising: a management unit for managing mapping, to the logical volume, of a second dynamically allocated storage area volume in an external storage apparatus, and also managing a management unit for a storage area in the second dynamically allocated storage area volume for storing data sent from the host computer; a first dynamically allocated storage area volume creation unit for creating, when creating the first dynamically allocated storage area volume in accordance with an externally given command, the first dynamically allocated storage area volume by setting a management unit for the first dynamically allocated storage area volume based on a management unit for a storage area in the second dynamically allocated storage area volume; and a write data writing unit for writing, in accordance with a command from the host computer, the write data sent from the host computer to a storage area in a relevant second dynamically allocated storage area volume.