Patent ID: 8825972

Claim:
A method for performing backups of a data set, wherein the data set comprises a plurality of data items, the method comprising: initiating a partial backup of the data set, wherein said partial backup includes less than all of the data set; wherein as part of said partial backup, the method comprises: conveying a first subset of the plurality of data items to a deduplication engine, wherein the first subset comprises data items that are new or have changed since a previous backup of the data set; generating an extents catalog for the partial backup which fully describes all of the data set; retrieving references associated with a second subset of the plurality of data items from the extents catalog, wherein the second subset comprises data items that are unchanged since a previous backup of the data set; and conveying references associated with the second subset of data items to the deduplication engine, wherein said references comprise identifications of one or more previous images corresponding to previous full or partial backups of the data set; at the deduplication engine: generating fingerprints for the first subset of the plurality of data items; creating a reference map and storing the fingerprints in said reference map; and receiving references associated with the second subset of data items and storing said references in the reference map.