Re: Inheriting a "interesting" recovery process

On 8/4/06, stv <stvsmth_at_gmail.com> wrote:
>
> Greetings all,
>
> Summary
> =======
> I'm a newbie Oracle DBA in a new job [non-profit in a small town, life
> is like that sometimes ;-) ]. I'm busting my butt reading up on
> everything I can, but there is one issue that I want to understand
> immediately: RECOVERY. Right now, we are covered only by a nightly
> export using the EXP utility. Archived redo logs exist, but are not
> backed up.
>
> Exactly how much data do we stand to lose? My guess is anything that
> happened after the export (i.e. the redo logs don't help much as
> things stand), but I'm not sure of that.

absolutely correct. Mogens comment about disabling archiving is probably not something I'd have said, but he is correct that if you lose your database (or bits of it) then you won't be able to recover, you'd have to create a new db and import.

What I'd have suggested, and indeed have done in my new position, is that you write immediately to the business owners, and cc your bosses pointing out that currently they could lose a whole days worth of work and that you can fix it really quite quickly by implementing a new backup regime. As you are on quite a recent release of Oracle I'd suggest you skip the whole 'BEGIN ...END BACKUP' thing and go straight to Recovery Manager (or RMAN). You can of course read about it in the docs and indeed at http://www.oracle-base.com/articles/9i/RecoveryManager9i.php though you'll want to skip the cataog for now.

Does EXP have read consistency like a normal select? Or will there be
> some gray areas in the dump file if open transactions existed at the
> time of export?

for each table by default. CONSISTENT=Y for the whole operation.

-- 
Niall Litchfield
Oracle DBA
http://www.orawin.info

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