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Re: recover question

From: Howard J. Rogers <>
Date: 28 Jul 2004 19:02:09 -0700
Message-ID: <>

"Tom" <> wrote in message news:<>...
> > Only if you make it into one, by not backing up your control file
> > regularly.
> thats great - thanks for this clarification, thats all i was after

I'm late to the party, I realise. But I hope you don't think that means 'use O/S techniques to regularly backup your control file'. I notice another post of yours where you mention a 'catch-22': "without the control file the instance can't be mounted to enable RMAN to restore the instance and therefore extract the control file from the backup?"

With regard to your last point first: there's a lot of sloppy language there. RMAN doesn't restore instances, for a start. It restores component parts of a database (and then recovers them). Instances aren't mounted: Control Files are. And hence there is no catch 22. You can create an instance without a control file. And RMAN can use that area of shared memory then to extract a control file from an RMAN backup that happens to include one. And once you've done that, you can then mount that control file and recover the rest of your database. So there's no catch-22, and there is absolutely no need to resort to O/S backups of any part of your database to make an RMAN backup usable even without a catalog database.

For the specifics on how to avoid the catch-22 which isn't actually a catch-22 at all, search for the phrase 'performing disaster recovery'. Additionally and a bit more specifically, have a search for the phrase 'Performing Recovery with a Backup Control File and No Recovery Catalog'... that should lead you to a description of how you extract a control file autobackup from an RMAN backup using nothing more than an instance. The specific step you'd be after would be something like:

RESTORE CONTROLFILE FROM AUTOBACKUP ...which needs nothing very much more exciting than a preliminary 'startup nomount' and a 'set dbid' command to work.

The short answer is, in other words: you do not need anything more than RMAN backups to recover a 9i+ database. O/S backups of any database component have become redundant with 9i, and are definitely not needed.

HJR Received on Wed Jul 28 2004 - 21:02:09 CDT

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