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Re: Recovery From Hot Backup

From: Howard J. Rogers <howardjr_at_www.com>
Date: Wed, 4 Oct 2000 10:17:54 +1000
Message-ID: <39da6b1d@news.iprimus.com.au>

<perfect_golf_at_my-deja.com> wrote in message news:8rd8or$6ih$1_at_nnrp1.deja.com...
> Scenario: I do a hot backup every night which includes backing up all
> tablespaces, control files, archive log files & parameter file. The
> redo log files are not backed up. This is based on Oracles backup/
> recovery documentation.
>
> Question: If I loss all the online redo log file(s), how do I recover
> these file(s)???
>

Short answer is, you don't.

You'd recover what's left of your database with a 'recover database until cancel' -when the system prompts to apply the missing online log, you tell it not to bother. You then have to do an 'open database resetlogs' -thereby invalidating all prior backups and archives. Time for a massive clean-up operation.

Your question begs a few others, however. Such as 'how likely is it that you'd lose *all* the members of any redo log group?' -because I'm sure you've mirrored them on separate devices and controllers, and if you've any sense, you'll have done three-way mirroring.

If you lost all three members of a group, properly mirrored, I would suspect that you've got rather more to worry about than recovering a database -for that to happen, we're probably talking about you being hit by an asteroid.

In other words, archived and online redo logs protect the datafiles; mirroring is the mechanism Oracle uses to protect the redo logs themselves.

Incidentally, how do you do your backup of the controlfile? I hope you're not just copying it, at the operating system. It will be internally inconsistent if so -that's what the 'alter database backup controlfile to 'blah/blah/bong' command was invented for (though the trace file is much the better option).

Regards
HJR
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Tue Oct 03 2000 - 19:17:54 CDT

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