Patent ID: 7694088

Claim:
A system comprising: a processor; a memory medium coupled to the processor which stores a plurality of backup images of a source data set, including a first backup image and a second backup image; and a backup manager; wherein the second backup image comprises at least one data block containing an updated version of a corresponding data block in the first backup image; wherein the backup manager is configured to: maintain a first image map and a second image map corresponding to the first and second backup images, respectively, wherein each image map of the first and second image maps includes a plurality of entries pointing to data blocks of the corresponding backup image; in response to a request to create a first aggregate backup image of the source data set, establish a first aggregate image map including indirect pointers that point to one or more entries in each of the first and second image maps, wherein the indirect pointers reference most recently backed up versions of data blocks of the source data set; and wherein the plurality of backup images includes a third backup image, wherein the backup manager is further configured to: maintain a third image map corresponding to the third backup image including a plurality of entries pointing to data blocks of the third backup image; and, in response to a second request to create a second aggregate backup image of the source data set, establish a second aggregate image map including a first indirect pointer to an entry in the first aggregate image map and a second indirect pointer that points to an entry of the third image map.