Re: [Veritas-bu] RMAN Recovery issue and Netbackup 7.1.0.2

If your original backup had 6 channels but they didn’t all start at same time OR some restarted due to some issue it is possible some of the streams are on tapes used by other streams in which case it has to wait until the first stream that used the tape finishes restoring (even if it is not yet using that tape for the restore).

I’ve not seen this for RMAN yet but did see it recently in the extreme for a rather large 4 stream DB backup. All 4 streams kicked off normally using 4 separate tapes. For some reason all of the streams had network timeouts so had to start a 2^nd attempt. On the second attempt stream1 used the tape for stream2, stream3 use the tape for stream1 etc… so when we did the restore it had to finish the first stream restore completely before it started the 2^nd and then the 3^rd and finally the 4^th. I truly wish there were a way to tell NBU NOT to use the same tape for multiple streams but the solutions I saw at the time I looked into this required separate pools or jobs or whatever that was a work around rather than a true fix. Since thankfully it doesn’t happen that often I elected not to address it. (Note that we have checkpoints turned on so on the re-attempt it did not start over from scratch – if it had we might not have had the issue but then the backup window would have taken longer.)

Jeffrey C. Lightner

Sr. UNIX Administrator

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Wayne T Smith
Sent: Friday, December 13, 2013 10:29 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] RMAN Recovery issue and Netbackup 7.1.0.2

It's been several years since I've had tape, but it sounds to me like the DBA has done everything correctly for 6 channels. The problem, if you can call it a problem, is that the backup server (media server) has only or is allowed only 3 tape drives for the restore. On the other hand, perhaps the files being requested on the 6 channels are stored on only 3 tapes. You can ask for 6 at a time, but each tape can only be in one place at any point in time.

There's nothing special about RMAN ... it's just a program that backs up the various parts of a database, keeps track of the backups, and when it comes time to recover a database, or a portion of it, requests the images from the backup system.

IMHO, the DBA was totally wrong to be screaming, but is probably right that this is a NetBackup issue (if he thinks the performance of 6 active streams will significantly outperform 3 active streams -- it might).

Guaranteeing that 6 backups streams will be written to 6 separate tapes could be a daunting task. I avoided this for restores of recently backups, when I had tape, by having backups go to a disk pool and then later to go tape.

Cheers, Wayne

On Fri, Dec 13, 2013 at 9:46 AM, Dennis Peacock <nbu-forum AT backupcentral DOT com> wrote

, in part

OK...please help me out here if you can.

Client RMAN backup ran on client server corvette via master server stingray.
Tapes were removed and shipped to another location for RMAN recovery.
Backup was done via allocating 6 channels.
Recovery is only using 3 channels. Why?
All boxes are Netbackup 7.1x and Linux RedHat.
DBA is screaming that it's a Netbackup issue....and I can't figure out why this is a Netbackup issue.

Can you help me understand more about RMAN backup/recovery and Netbackup??? Please????

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