| 摘要 |
<p>The file recovery system produces a back up tape (4) before the file (2) is produced, and an image of the file block is produced after updating of the file. These continue to be accumulated in a group of journal tapes (6). The tapes are advanced periodically under control of a tape advance process, which also produces a new back up tape (4'). When a fault appears in a file the newly produced back up file (4') and the journal file (6) are used to recover the file at the version immediately prior to appearance of the fault.</p> |
