Patent ID: 8010756
Filing Date: 2011-08-30
Classification: G06F,Y10S

Abstract:
1. A method for changing a time reference for a point-in-time volume that has previously been established to a current time reference of a source volume, the method comprising: maintaining mapping data comprising a delta table and a migration table, the delta table including entries identifying data chunks that have been modified on the source volume, said modification being determined by detecting a write operation directed to the source volume, the migration table including entries identifying data chunks that have been migrated from the source volume to the point-in-time volume; and changing the time reference for the point-in-time volume to the current time reference of the source volume, following the previous establishment of the point-in-time volume and intervening writes to the source volume, by transferring modified data chunks corresponding to the entries in the delta table, with at least one read operation directed to the source volume and at least one write operation directed to the point-in-time volume.