Patent ID: 8762671

Claim:
A storage apparatus, comprising: a controller connected to a host system; and a storage device connected to the controller; wherein the storage device is configured to provide a page, which is an actual storage area, to a logical volume created in the controller, a duplicated volume which is created in the controller and is a duplicate of the to logical volume, and a snapshot volume created in the controller for storing data to be saved by a snapshot, wherein the controller is configured to provide the logical volume, the duplicated volume, and the snapshot volume to the host system, wherein when allocating the page provided by the storage device to the duplicated volume, the controller is configured to allocate the page in a stripe unit of a data size that can be read by one read command, to the storage device, wherein the controller is configured to allocate the page in the stripe unit to the duplicated volume based on a mapping table for associating a position of a storage area in the duplicated volume with a position of a storage area in the storage device, wherein the mapping table is constituted from a volume management table, a volume area management table, and a data area management table; and wherein the controller is configured to: manage the logical volume, the duplicated volume, and the snapshot volume by associating them with each other based on the volume management table; manage a storage area in the duplicated volume in a slot unit, which is a minimum storage area for storing data, based on the volume area management table; and manage a storage area in the duplicated volume in a stripe unit based on the data area management table.