Patent ID: 8832027

Claim:
A method of tracking changes between snapshots of a source storage, the method comprising: at time t(1), starting tracking, in a change log, locations in a source storage of all blocks that are changed after time t(1); between time t(1) and time t(3), changing a block in the source storage by a file system executing a write command; at time t(3), starting a first snapshot operation on the source storage, the first snapshot operation including creating a first snapshot of the source storage by, for each write command including a target location received by the file system after time t(3), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command; after time t(3), creating a first image backup using the first snapshot; at time t(8), starting a second snapshot operation on the source storage, the second snapshot operation including creating a second snapshot of the source storage by, for each write command including a target location received by the file system after time t(8), copying a block at the target location for safekeeping prior to changing the block at the target location by the file system executing the write command; and at time t(11), creating an incremental image backup that includes all blocks in the second snapshot that are tracked as having been changed in the change log after time t(1).