About checking for data loss
To detect data loss, the NetBackup bptm process reads the tape position and then verifies the actual position against the expected position.
If the actual position is less than the expected position at the end of the backup process, the following events occur:
The tape is frozen.
The backup fails.
The following error message entry is written to the bptm log:
FREEZING media id xxxxxx, External event caused rewind during write, all data on media is lost