Patent ID: 7587564

Claim:
A method for managing data versions, the method comprises: receiving a first request to generate a first version of a source volume; selectively updating a first control data structure that is indicative of changes of blocks of data associated with different versions of the source volume, in response to the first request, to reflect at least one latest modified block of data that was modified between a first point in time associated with the first version and a second point in time associated with a second version of the source volume, wherein information representative of different versions of the source volume is stored in a target storage unit, and wherein first ones of the blocks of data that remain unchanged in the different versions of the source volume are shared among the different versions; selectively copying blocks of data from the different versions of the source volume to the target storage unit in response to a content of the first control data structure; and maintaining an additional control data structure indicative of oldest modified blocks of data of the different versions that have not been copied to the target storage unit.