Re: RMAN Question

From: Mladen Gogala <>
Date: Wed, 2 Jan 2013 13:05:14 +0000 (UTC)
Message-ID: <>

On Wed, 02 Jan 2013 03:15:02 -0800, billshatner71 wrote:

> Hi.
> Because of space issues I'd like to keep one backupset on tape and allow
> that to get copied to tape each night but still be able to recover from

You probably want to keep a copy on disk and copy it to the tape for archiving?

> previous backups from tape.
> What's the best way of doing this?
> Thanks.

Well, there are several ways of doing that. In my opinion, the best way of doing that is to use backup software which can do that automatically, like CommVault Simpana 9. Simpana can do de-duplication, so your disk backups will be small(er) and you will save some additional disk space. It can also automatically copy your backups to a different location. It uses RMAN in the background. That would probably require you yo switch backup software and convert all your important tapes from your current backup format to Simpana or keep two versions of backup software around, just in case. CommVault can help you with the migration projects.

Second way of doing that is to use VTL software like Data Domain or Firestreamer. Data Domain is sold by EMC and I encountered it several times. VTL organizes your disk into virtual tapes and pushes it to the real tape when the disk gets close to being full. It' configurable. VTL will also keep track of your tapes and generate bar codes for them. That probably doesn't require you to change backup software, at least not for Data Domain, which is the one I have worked with.

The third way would be to maintain a standby database and backup the standby database directly to tape. That way, you would have your files up to date on a separate machine and all you need on the tapes. Restoring the primary would be rather easy, all you need to do is to change DB_UNIQUE_NAME to that of the standby and RMAN catalog would automatically recognize those backups as the primary DB backups. That would also cost you an additional machine. No additional license is needed for the physical standby database, unless it is activated into an active standby database, at which point it requires a full EE license for the platform it is running on. Active DG is not available with the standard edition and is not available before Oracle 11G.

The fourth way is to do nightly RMAN backup to disk and back it up to tape, using the normal file system backup. The advantage of that solution is that it is cheap and will not cost you a dime. The disadvantage is that you will have rough time, should you ever attempt to restore an old backup. The procedure is the following:

  1. You would do "RESTORE DATABASE UNTIL TIME "...." and your RMAN catalog will duly return the disk paths as they were when the backup was taken.
  2. You would then have to manually restore both the data files and the needed archive logs from the tapes. It would probably involve browsing the backup catalog and finding all those tapes and locating all those tapes manually.

The fifth way, which may not be available, based on your DB version, would be to backup the data files to the flashback recovery area as copy, maintain that copy for recovery using "RECOVER COPY OF DATABASE" and then, when the recovery is finished, backup the entire FRA to tape using "BACKUP RECOVERY AREA". That be free but would include some setup effort and a performance hit, while the DB copy is being recovered. That is available as of 10G, but I really wouldn't try it with anything older than

I have probably missed a way or two, but this should give you enough choice for a start. Happy New Year.

Mladen Gogala
The Oracle Whisperer
Received on Wed Jan 02 2013 - 14:05:14 CET

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