Patent ID: 7882064

Claim:
A method of file system replication comprising: determining using a processor whether one of a plurality of files included in an original file system has been updated since a previous replication, including comparing a current content handle associated with the file at current time and a previous content handle associated with the file at an earlier time, wherein: each content handle is derived based at least in part on a multi-layered hierarchical representation of the file; the multi-layered hierarchical representation includes a bottom layer that includes a plurality of bottom layer nodes that corresponds to a plurality of data segments included in the file, and a second layer that includes a plurality of second layer nodes each being derived based at least in part on some of the bottom layer nodes; each content handle is derived based on one or more nodes in the hierarchical representation of the file that are included in a layer other than the bottom layer; and in the event that the file has been updated, locating among the plurality of data segments a previously not stored data segment; replicating the previously not stored data segment; and locating among the plurality of data segments a previously stored data segment that is newly referenced by the file, wherein locating the previously stored data segment is based at least in part on at least some of the plurality of data segment references, and the previously stored data segment is not replicated.