Patent ID: 8060468
Filing Date: 2011-11-15
Classification: G06F

Abstract:
1. A storage system, comprising: a processor; a replication creation unit configured to create a replication of write data written from a computer into a volume as necessary; a journal creation unit configured to create a journal containing said write data and control information concerning the writing of said write data in said volume each time said write data is written in said volume; a recovery unit configured to recover a past status of said write data based on said replication of write data and said journal; a creation and management unit configured to create and managing information representing a data recovery candidate point as a candidate of a point in time for recovering said write data; and a redundancy elimination unit configured to use one or more data recovery candidate points and specifying a section containing said journal and said replication of write data, to check a redundancy relation of a write range in said volume of write data written from computer into said volume contained in said journal regarding one or more said journals in said section, and to execute redundancy elimination processing of merging a plurality of said replications of write data or a plurality of said journals into a single replication of write data or a single journal based on the check result; wherein said redundancy elimination unit checks whether or not said redundancy relation of said write range matches at least one of the following patterns: a first pattern in which said write data includes precedent write data written before said one or more journals and said write data includes subsequent write data written subsequent to said one or more journals, and an address range of said subsequent write data is contained within an address range of said precedent write data; a second pattern in which said address range of said precedent write data partially overlaps with said address range of said subsequent write data; a third pattern in which said address range of said precedent write data is contained within said address range of said subsequent write data; a fourth pattern in which said address range of said precedent write data is the same as said address range of said subsequent write data.