Patent ID: 7366859

Claim:
A method of incremental backup of a storage device, comprising: (a) generating a bitmap of selected physical storage units of a storage device, with all selected physical storage units marked; (b) selecting an area of the storage device for backup; (c) reading descriptors of logical storage units of the selected area; (d) comparing hash function values of the descriptors of the logical storage units of the selected area with hash function values of descriptors of already archived logical storage units; (e) for physical storage units related to logical storage units of the selected area whose descriptors are not identical to the descriptors of the archived logical storage units, based on step (d), checking if these physical storage units need to be backed up and unmarking, in the bitmap, those physical storage units that correspond to the archived logical storage units with coincident descriptors; and (f) backing up contents of physical storage units identified as marked in the bitmap in step (e).