US Patent 7966448 Storage apparatus and data writing method

A storage apparatus includes: a management unit for managing mapping, to a 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 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 the 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.