With the ATTENDED OFF option, you can specify that no operator will be present during a backup.
The operator does not need to respond to prompts during the backup.
The archive devices can be stacker drives, which automatically load a set of tapes into a single drive. You can use stacker drives for both attended and unattended backups.
Unattended backup tries to detect all possible reasons for a backup failing except tape media failure, and report any potential errors before attempting the backup, such as available space on disk or tape, and consistent size and block factor.
For unattended backup to disk, SAP Sybase IQ first tests whether there is enough free disk space for the backup, However, it does not pre-allocate the backup files to reserve the space. If another user writes to that disk and as a result there is not enough room for the backup, the backup fails when disk space runs out.
For backup to tape, you must estimate how much data each tape will hold, and specify that number of kilobytes in the TO archive_device parameter of the BACKUP command. The backup program checks information stored internally to see how much room it needs to back up your database. If it determines that there is enough room on the tape, the backup proceeds. However, if you overestimate the amount of space available on the tape(s) and the backup runs out of space, the backup fails at that point.
If you omit the SIZE parameter for an unattended backup, the entire backup must fit on one tape.
If you are using a third-party backup product, the vendor information string needs to convey any information needed for the backup, such as the specification of devices, size of files, and stacker drives. See your vendor's documentation for details.