Patent ID: 8745343

Claim:
A method of resynchronising a previous duplication, started at a first time, of a source logical drive on a destination logical drive, the method comprising: providing first and second snapshots taken at said first time, said first snapshot comprising data and metadata relating to data which has changed since said first time and said second snapshot comprising only metadata relating to data which has changed since said first time; subsequent to said previous duplication, deleting said first snapshot; tracking, using said second snapshot, changes made to the data on said source logical drive since said first time; starting a resynchronisation operation at a second time later than said first time; creating a third snapshot at said second time, said third snapshot being arranged to comprise data and metadata relating to data which has changed since said second time; utilising said second and third snapshots, copying only data which has changed in between said first and second times from said source logical drive to said destination logical drive.