RE: question about rman

Chris - We use RMAN to back up to disk, then copy the files to tape. We found the MML piece VERY expensive.

    The part I don't understand about your original note is the part about the disappearing mount points. We write the backup to disk, and yes if we need to perform a recovery we will need to ensure the file RMAN needs is available at that exact point on disk, with the same name. If the file has been deleted, then we will have to bring the file back from tape first.

Dennis Williams
DBA, 40%OCP
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Tuesday, January 21, 2003 2:05 PM
To: Multiple recipients of list ORACLE-L

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.    

-----Original Message-----
Sent: Tuesday, January 21, 2003 1:31 PM
To: Multiple recipients of list ORACLE-L

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!

-----Original Message-----
Sent: Tuesday, January 21, 2003 10:45 AM To: Multiple recipients of list ORACLE-L

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)

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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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