Forum Discussion

benjayhal's avatar
Level 3
6 years ago

Netbackup Tape writing behaviour

Hello All,

I have a question about tape retention. The question may be stupid and /i think i know the answer, but I am not sure.

In a situation where netbackup is writing a frontend(client to tape)  or SLP driven deduplication backup (disk to tape).. and for some reason the backup fails.

What happens to the data that has already been written on the tape? Is it retained as per the policy schedule retention that is defined or is it discarded?

Also what happens to such a tape where the backup that was writing to it failed before it could complete?

Is there a way of identifying such tapes? Maybe erasing them and putting them i nthe scratch pool?

Any help is fully appreciated.


Kind Regards,



7 Replies

  • If a job fails and has NOT spanned to another tape, then the tape is rewond to the beginning of the failed jobs, and an empty header is wriitten.  Therefore, the failed data is inaccessable and will be overwritten the next time the tape is used.

    If the failed backup has spanned to another tape, then the same is true, but only for the tape that is being written at the time the job fails.  Previous tapes used for the failed backups and not 'updated'.


    • Nicolai's avatar

      and if backup is multiplxed - e.g one good backup and one failed backup, the space used by the failed backup will be lost capacity until tape is returning to scratch status

      • benjayhal's avatar
        Level 3
        Thanks for the replies.Is there any way to easily identify tapes which were part of failed backups? That is a scenario where backups have spanned multiple tapes and failed
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