| 摘要 |
A system for deleting files or file segments in a backup system comprises file metadata containing a unique file fingerprint and stored in a metadata store, a file segment identifiable using a unique file segment fingerprint and stored in a content store, and, a data object referenced by a file metadata store entry and identified by the unique file fingerprint and contains a list with the segment fingerprints of each segment of the file. Actions on segments and data objects are carried out in chronological or receipt of command order and, to delete a file, the file is identified, the metadata store entry is marked, the reference to the metadata store entry for the file is removed from the data object and the marked metadata store entry is deleted. Each data object could describe more than one file and if it no longer describes any file as a result of deletion, the data object is removed. If no data object is linked to a file segment, the file segment is also removed. This system ensures that only data objects to which all references have been removed are actually removed from the data store. |
