Re: Help recovering from hotbackup

"Paul Brewer" <paul_at_paul.brewers.org.uk> wrote in message news:3e04bbe0_2_at_mk-nntp-1.news.uk.worldonline.com...
>
> "Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message
> news:osNM9.7412$jM5.20748_at_newsfeeds.bigpond.com...
> > > Howard,
> > >
> > > Go easy, please.
> > >
> > > What happens if you lose all the online redo logs (yes I know they are
> > > supposed to be multiplexed)?
> >
> > Actually, there's only ever one online log (OK, maybe briefly two,
whilst
> > one's being checkpointed). The other 'online logs' have of course
already
> > been backed up. That's what ARCH does.
> >
> > > Yes, you can recover the database, but surely you lose the last few
> > minutes
> > > worth of updates?
> > >
> >
> > Entirely true. But so what? That's not an argument for backing up the
> > online logs, is it? It's rather an argument for multiplexing.
> >
> > Suppose you backup the online logs, against all Oracle's advice, RMAN's
> > in-built capabilities, and my repeated entreaties not to. That was last
> > night. How is restoring a 9-hour old 'online log' going to help you
*not*
> > lose the last transactions that were contained in the real-life online
> logs?
> >
> > If you lose your online logs, you have absolutely no alternative but to
do
> a
> > 'recover until cancel', cancel when it prompts you for what you know to
be
> > the missing logs, and then open resetlogs. At which point you get your
> > online logs back... but, yes, missing the last dollop of redo, and hence
> > with some lost transactions.
> >
> > The *only* thing you can do to prevent that is multiplex.
> >
> > Backing up the online logs doesn't help at all.
> >
> > Cheers
> > HJR
> >
> >
> >
> > > Regards,
> > > Paul
> > >
> > >
> > >
> >
> >
>
> Howard,
>
> Sorry, I didn't phrase the question properly. I meant to ask: 'What
happens
> if you lose all the (multiplexed) members of the current online redo log'?
>
> But you have already answered the question.

Ah. Actually, if you lose all multiplexed members of the current log (and I tend to suggest 3-way multiplexing to try and avoid this situation, but it really depends on performance), the real answer is: go and get a new job. Preferably as far away from IT as possible. Oh.. and stop wearing nylon underpants.

And never, ever get on the same aeroplane as me.

Your middle name is obviously Jonah. Your great-great-grandparents probably won tickets on the maiden voyage of the Titanic. And your grand-parents almost certainly worked on the Apollo 13 project.

Either that, or stop buying IBM hard disks, and switch to Seagate.

;-)
HJR
>
> Thanks,
> Paul
>
>
>
Received on Sat Dec 21 2002 - 13:23:07 CST