Patent ID: 7266654
Filing Date: 2007-09-04
Classification: G06F,Y10S

Abstract:
1. A storage system comprising a server apparatus including at least one storage interface, and, at least one disk apparatus connected to the storage interface including an operational volume which performs ordinary read/write and a differential volume which stores differential data of snapshot of the operational volume, wherein: the server apparatus includes: the snapshot management part: wherein said snapshot management part includes a differential block management table comprising a plurality of columns each having fields for differential volume block address, possession bit map, and preceding copy area address for recording said location information; and wherein said differential volume address represents a differential volume block address in said differential volume, said possession bit map represents whether the block in said differential volume indicated by said differential volume block address is used in respective snapshots, and said preceding copy area address indicates whether a block in said differential volume indicated by said differential volume block address is being used as a preceding copy area or not, and if being used as a preceding copy area, a block address of the copied block in said preceding copy area is indicated in the field of said preceding copy area address.