----- Original Message -----
Sent: Tuesday, January 21, 2003 3:04
PM
Subject: RE: question about rman
The
problem is that if we try and backup to tape, we have to wait in the
queue. Depending on what is already there, we may have to wait a number
of hours before RMAN has the opportunity write data to the tape. Believe
me, we have tried to devise ways to predict when we could actually write to
tape but the sys admin has stated over and over that he has no control over
when a tape is available due to the queueing. In a cold backup this
implies unacceptable downtime. In a hot backup it means that the
database will be backed up over a very long period of
time.
So
if we first backup to disk and then let omniback take the data to tape
whenever it gets around to it, we'll still be able to due a recovery through
RMAN if the necessary files are on tape (a place that RMAN is unaware
of).
note: obviously we are going to have to test this but
i'd like to know that it is possible before i go through the trouble of
coordinating something with the sys admins.
thank you.
I
guess my first question is why not just backup to tape through the Omniback
MML layer? Or, if you prefer to go to disk you can backup to disk with RMAN
and then backup the backupset to tape through the MML with RMAN again.
If you try to restore from an RMAN backup, and the required backup pieces
are not there, RMAN will let you know.
HTH,
Robert
Robert G. Freeman
Technical
Management Consultant
TUSC - The Oracle Experts
www.tusc.com
904.708.5076 Cell (it's everywhere that I am!)
Author of
several books you can find on Amazon.com!
I could test this myself but that would require
coordination with the system administrators and they always seem to think
their time is too important for testing. :)
i would like to implement RMAN in and 8.1.7.2 oltp
environment and 9.2.0 warehouse environment. We use Omniback as an
enterprise wide backup solution. Don't know if this is version
specific so I thought I would mention. Here's the
question....
Currently we are doing os level backups for both
environments. We take the backup to disk and then omniback backs up
the mountpoints we write to. A problem we have is that we are unable
to predict when omniback will get to our backup mountpoints
due to the fact that there is a queue that serializes our
backups and other servers are place in that queue ahead of us. This
is a factor in our warehouse environment as it makes the downtime of a
cold backup unpredictable. In the oltp environment this makes the
length of backups unpredictable and GREATLY increases redo
generation. The only option we have is to first backup to
disk.
So here's my problem with RMAN...if we backup to disk
through rman and then omniback takes that data to tape and the backup
mountpoints are overwritten the very next time a backup is taken then
RMAN's ability to find the necessary files is compromised if the
redundancy is set to anything >1 (or whatever recovery window the
translates to). So if I try and restore a database in either
environment and RMAN can't find the necesary file(s) will it return a
message asking where those files are? ...at which point i would call
the sys admins to restore the particular file. or would i be
hosed?
thank you very much for any responses.
(i plan on buying 9i rman soon but didn't want to wait on
this)
chris
(wishing for dedicated tape drives)
