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Re: question about rman

From: Ruth Gramolini <>
Date: Wed, 22 Jan 2003 06:28:51 -0800
Message-ID: <>

question about rmanI am jumping in late on this thread and may be way off the mark but I do all my backups to disk and put them on tape using the OS backup facility. When recovery is needed I just put the backupsets back on the original disk. Then rman isn't confused at all. If omniback can put the files onto tape at a later time, you can still do backup whenever you want. I work for the State of Vermont, and budget contraints force us to find the least expensive solution. Rman, tape, and the OS backup software are the cheapest way and it works. I have recovered many times using this method.


  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-----
    From: Freeman Robert - IL []     Sent: Tuesday, January 21, 2003 1:31 PM     To: Multiple recipients of list ORACLE-L     Subject: RE: question about rman

    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     904.708.5076 Cell (it's everywhere that I am!)     Author of several books you can find on!

      -----Original Message-----
      From: Chris Stephens []
      Sent: Tuesday, January 21, 2003 10:45 AM
      To: Multiple recipients of list ORACLE-L
      Subject: question about rman

      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 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? 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) 


      (wishing for dedicated tape drives) 


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Author: Ruth Gramolini

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