Patent ID: 7831789

Claim:
A method for combining file-level and block-level backups for a fast incremental backup of a storage device, the method comprising: (a) creating a bitmap of blocks of the storage device with all blocks that require backing up being marked in the bitmap; (b) extracting descriptors of the files and directories from a descriptors area of the storage device; (c) discarding at least some of the descriptors from a set of descriptors associated with each file and then generating a common hash value of a resulting set of descriptors; (d) recognizing identical hash values related to a prior backup of the storage device and to a current state of the storage device; (e) checking coincidence of blocks that form a single file, wherein the descriptors of the files have identical hash values, and, for at least some of the blocks that form the single file, comparing contents of the blocks; (f) unmarking, in the bitmap, the coincident blocks; (g) backing up contents of the blocks that are marked in the bitmap; and (h) storing pointers for coincident blocks, wherein the pointers point to blocks from the prior backup.