A copy procedure detects qualified data objects in a body of source data,
and copies the source data to a target storage unit except for
unqualified data objects, which are replaced with a prescribed bit
pattern. Following completion of the backup, a record is prepared
indicating that all data objects exist in the specified target storage,
regardless of whether each data object was replaced with a predetermined
bit pattern rather than being physically written to the specified target
storage. This process may be repeated in order to perform data
reclamation, effectively removing user files no longer qualifying for
backup.