Patent ID: 7861047
Filing Date: 2010-12-28
Classification: G06F

Abstract:
1. A storage device comprising: a plurality of disk drives storing data sent from a host device; and a control processor for controlling reading and writing of data to and from a first logical volume generated using storage areas of the plurality of disk drives, performing control to write old data stored in the first logical volume into a second logical volume as per-generational differential data, and managing differential data by providing in an area of a memory a snapshot management table for managing relationships of the per-generational differential data stored in the second logical volume, wherein the snapshot management table is used to generate a specific per-generational virtual logical volume, and the specific per-generational virtual logical volume is used to create a remote copy, wherein differential data between said first logical volume and said specific per-generational virtual logical volume is sent to another storage device as data for the remote copy, and wherein a first bitmap showing an area in which a differential occurred with respect to a previously created remote copy is created when updating the specific per-generational virtual logical volume, and a second bitmap showing the area of the differential data is created when writing the differential data to the second logical volume.