Re: Oracle 8i Standby Complete Recovery

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:YXwr9.54893$g9.159279_at_newsfeeds.bigpond.com...
>
> "Karen Abgarian" <abvk_at_apple.com> wrote in message
> news:3DADD79B.D4D01AE5_at_apple.com...
> > Some ideas that come to mind:
> >

A really big snip where Howard put paid to few of those ideas ;)

> > Another question I am trying to get answered: how does DG manage
> > TWO standby databases? What happens with redo data if one of them
> > is temporarily unavailable?
>
> It depends. You can configure some standbys to be 'must send to'
> destinations, and others to be 'desirable to send to'. The point about
Data
> Guard is that it's up to you how you configure it. The failure to archive
> to 'must send to' destinations *can* cause the primary to shutdown, or
might
> cause nothing very much to happen for the interim, followed by a massive
> catch up operation when transmission becomes possible again.

A nice feature with Data Guard is the ability for a Standby Database to automatically realise that some redo logs are missing and for it to automatically go off looking for where (hopefully) they might be. By setting a couple of parameters on the Standby DB (FAL_CLIENT and FAL_SERVER) basically makes the Standby DB behave in this manner:

Standby DB reading the paper waiting for the next log to arrive. It should be log 1234 but boy it's taking it's time. Eventually log 1238 arrives. "Shit" says the Standby DB, "Crystal Palace have lost again". It then puts the paper down and says "Shit, what happened to logs 1234, 1235, 1236 and 1237" !!

It then thinks, "wait a minute, I've got the phone number (make that service name) of my mate Standby 2 DB". "I'm a bit jealous of him to be honest as he's more *important* than me, being mandatory while I'm just optional. Still, he has he's uses and being the mandatory snob that he is should have the missing redo logs".

A quick tap on the shoulder of the mandatory standby DB (who indeed does have all the missing logs and is identified by the FAL_SERVER parameter) and he politely delivers them to the poor optional standby DB (who is identified by the mandatory DB via the FAL_CLIENT parameter).

Note the Primary DB could also have been used for this purpose.

I think it's pretty neat, despite all the bugs ;)

Richard

>
> HJR
>
>
> > Thank you for any answers.
> >
> > Regs
> > AK
> >
> >
> > Chris Forbis wrote:
> >
> > > I am looking into ways of recovering in the case of a major failer on
> > > a primary server. I have the idea to create a standby server, and
> > > this seems to take care of much of the work. The problem I see is
> > > when the primary system fails, and a log switch has not happened in
> > > the last 4 minutes, It seems I loss that 4 minutes of data because the
> > > log has not been archived and moved.
> > >
> > > Ideas of how to get 100% no data loss?
> > >
> > > Thanks
> > >
> > > Chris
> >
>
>
Received on Thu Oct 17 2002 - 09:03:55 CDT