Various embodiments of systems and methods for performing volume-based
incremental backups are disclosed. A method may involve generating a
snappoint of a volume. The snappoint indicates which portions (e.g.,
blocks or extents) of the volume have been modified between a time at
which the snappoint was generated and a time at which a subsequent
snappoint was generated. The method may also involve accessing
information mapping the file to the volume and, if the snappoint
identifies as having been modified any blocks of the volume to which the
file maps, copying those blocks from the subsequent snappoint to the
backup device. Portions not identified as having been modified by the
snappoint are not copied. Program instructions implementing such a method
may be stored on a computer accessible medium.