Backups primarily ensure quick recovery in case of system failure.
However, users who have deleted files can request file restorations from system backups. Because the Andrew File Servers view information in terms of volumes instead of individual files, it is only possible to tell which volumes have been copied to backup tape. It is not possible to determine which files are contained in a volume on backup tape. User, project, and bboard volumes receive a full backup one a month and receive incremental backups daily. An incremental backup saves only files that have changed since the last full backup.