I have spotted that each time tape drive cleaning is requested then tape currently in the drive is marked as FULL and only written like 1TB of various other data.
Can anybody advise why would that be? Unsure if this is an issue so this is something that I've spotted, at a time cleaning is required netbackup automatically marks tape as full prior to perform drive cleaning.
Also each time cleaning is needed I get the below alert from tape library:
Attention : Drive Warn or Crit Tape Alert flag
Event Code: 0x84 - tape alert
Element number: 0x1E, 30
Drive number: 0x04, 4
Tape Alert Flag: 0x15, 21
Tape Alert 0x15,21 is a cleaning required message from the drive. How often does the tape drive request cleaning ?
Cleaning request should be rare - if you see a lot of request, the drive may be faulty.
To be on the safe side - inspect the tape in use - is the same tape repeatedly being requested, but never written ?
remember you can always freeze a tape until a reasonable suspicion is confirmed or not.
Does the tape marked full also get frozen/suspended by Netbackup ?
Same issues posted back in 2015:
I don't think those two events are linked.
When writing a tape, the OS see the tape as a continuous number of sectors. When the tape drives detect the EOM (end of media) marker on the tape, the tape drives send a signal to the OS that the tape is full.
Netbackup as such doesn't measurer remaining capacity on a tape, it can't. Netbackup only measure the number of sectors written to tape (consumed capacity).
To narrow down what is happening, look out for SCSI sense codes in the event log. A code consist of a sense key, a additional sense code (ASC) and additional sense code qualifier (ASCQ). What they mean can ben looked-up at this Wikipedia page: https://en.wikipedia.org/wiki/Key_Code_Qualifier