Patent ID: 8214406

Claim:
A method for performing an incremental block-based backup, comprising: using a processor to record that during a prior backup one or more metadata block locations contained file system metadata associated with a file system tree as opposed to data associated with the file system tree, including grouping the recorded metadata block locations according to nodes in the file system tree and recording with each recorded metadata block location (1) a unique identifier corresponding to that node and (2) a unique identifier corresponding to a parent node of that node; obtaining a list of changed block locations, wherein the list of changed block locations comprises a list of entries, including at least one changed data block location entry and at least one changed metadata block location entry, and wherein the at least one changed data block location entry stores a location at which a data block that has changed since the prior backup is located, and wherein the at least one changed metadata block location entry stores a location at which file a system metadata block that has changed since the prior backup is located, and wherein the inclusion of each changed data block location entry or each changed metadata block location entry on the list indicates that the block corresponding to the entry has been changed since the prior backup; using the processor to compare the recorded metadata block locations and the list of changed block locations in order to determine those block locations in the list of changed block locations which contained file system metadata during the prior backup; determining a changed portion of the file system tree that has changed since the prior backup based at least in part on those block locations in the list of changed block locations which contained file system metadata during the prior backup, including mapping at least one of those block locations and mapping the corresponding node in the file system tree to a parent node of the corresponding node; obtaining incremental metadata for the changed portion of the file system tree; and storing the incremental metadata in storage, wherein there is at least some file system metadata associated with an unchanged portion of the file system tree that is not stored.