Delta catalogs in a backup system

摘要

A method and mechanism for performing data backups in a computing system. A "delta" catalog is utilized for the maintenance of data backups. The delta catalog includes a backed up object table and an extent map. For a given backup, the backed up object table update stores entries which identify only those objects backed up during that backup. The backed up object table is further configured to store entries which identify objects which were deleted between the time of a prior backup procedure and a current backup procedure. The extent map is configured identify all objects present in the system at the time of a particular backup. The extent map identifies the objects which were present as one or more sequences of entries in the backed up object table.