[Veritas-bu] RESOLVED: Each stream uses different tape for RMAN 1-channel backup
2008-06-17 13:41:11
I finally resolved this issue and the cause was something I never would
have suspected. It turned out that my tape drives were flagged as
"needs cleaning", which apparently causes NBU to unload a tape
immediately after a stream is written and ignore any type of normal
unmount waiting period. I reset the mount time on my drives to clear
the flag, and suddenly the same backup job used one tape.
I need to give credit to the folks on the Symantec forum for the solution:
https://forums.symantec.com/rss/message?board.id=21&message.id=41109
Bryan
Bryan S. Leaman wrote:
> I am running an RMAN backup to a storage unit with multiple drives on
> 6.5.1. The RMAN backup is allocating only one channel as it's a small
> database and there is no need to use multiple drives. However I'm
> noticing that for each new RMAN backup piece, NBU mounts a different
> tape in another drive instead of using the one that is already loaded
> which was used for the previous piece. So it ends up alternating back
> and forth between several tapes and using many drives in the process.
> This doesn't seem very efficient. Is there any way to prevent this?
> I don't remember seeing this with 3.4 from which I am in the process
> of upgrading.
>
> Example: RMAN backup with one channel, and 3 backup pieces
>
> Stream/piece 1: tape 1 - drive 3
> Stream/piece 2: tape 2 - drive 2
> Stream/piece 3: tape 1 - drive 1
>
> This behavior also seems to be the same that some of us have seen
> recently with catalog backups, in which it will create several
> streams/jobs and put them on different tapes for one catalog backup
> (thread "Catalog backup = 4 separate jobs???").
>
> Thanks for any help on this.
>
> Bryan
>
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