VMware, Inc.
Virtual machine image file synchronization using delta bitmaps and delta files

Abstract:

A synchronization process for virtual-machine images (and other segmented files) provides for generating a "delta" bitmap indicating which segments (e.g., clusters) of a first virtual-machine image were changed to obtain a second (e.g., updated) virtual-machine image on a source node. The delta bitmap can be applied to the second-virtual-machine image to generate a delta file. The delta file can be sent along with the delta bitmap to a target node that already has a copy of the first virtual-machine image. The transferred delta bitmap and delta file can then be used on the target node to generate a replica of the second virtual-machine image, thereby effecting synchronization. In variations, different bitmaps and delta files can be transferred to optimize the synchronization process.