Re: Backup: 3 hours & Restore: 10 hours????

I don't know about RMAN but if it works anything like Omniback (From HP) the restore can take MUCH longer than the backup. It all depends on the number of streams to the tape you have. For exmaple, if you have 1 stream, that means 1 file is backed up at a time. You end up with a tape that looks like this (assume each letter is a different file):

abcdefghijklm....

If you have a fast backup system, you can change the stream value to keep you tape moving. This makes for a fast backup but a slower recovery. The streams will back up files in a round robin sequence so you might get something like (each letter/number combo is part of the same file):

a1b1c1d1a2b2d2e1a3b3e2f1a4g1e3f2....

The above is with 4 streams. The advantage of the former is a faster recovery time but slower backup. The reverse is true for the latter. Since we can afford little down time we do the second method.

Hope that helps
Vince

On Tue, 27 Aug 2002 10:43:39 -0400, Forte Agent <1443131_at_usenetplanet.com> wrote:

>
>I am not a RMAN expert, so here is a question.
>
>We have a database that takes about 3 hours to backup to tape device
>using RMAN. When we restore it, often times it takes more than 10
>hours, even though backup took only about 3 hours. I was told the
>reason is the fact that RMAN is restoring datafiles out of order that
>they were backed up. Therefore, tape device has to travel back and
>forth looking for files in tapes, taking up times much longer than it
>took to back them up. Is there some way to prevent it, somehow direct
>RMAN to restore files in order they were backed up, regardless what
>kind of database recovery you are performing? Thank you in advance.
Received on Tue Aug 27 2002 - 14:37:46 CDT