Re: recovering from archived redo logs

> 1. a copy of a current control file (or a (binary) backup controlfile),
> Doesn't matter if I don't have current copies of redo logs because all the
> redo is in the archives.

If you've lost the redo logs you can't do a complete recovery - only an incomplete recovery
(because your most recent transactions are in the current redologs) ... you'll have to open
using resetlogs

> But f i don't have current redo logs and try rebuilding a control file
from
> a trace copy, I can't recover at all.

use recover database using backup controlfile until cancel ... cancel ... alter database open resetlogs

> 2. Copies of CURRENT redo logs and I rebuild control file from a trace
> control file. Oracle seems to get highest SCN from current logs when it
> rebuilds the control file, so it says 'aha, SCN in data files is below
that
> in the archived logs, recovery needed.'

You can not do a hot/consistent backup of the online redologs - that's why it's recommend
to put online redologs on seperate physical disks (seperated from your data that is) ... chances of having more
than one disk crashing at the same time is not that high (unless you blow a controller) ... also your archives should reside a seperated physical disks ....
In other words - you can never ever restore online redologs from tape (in a hotbackup situation) and use them to recover ... you'll always have to do an incomplete (until cancel, until scn, until time, ...) recovery

check out http://www.lazydba.com/xcomment.pl?dbascripts:8 for possible recovery scenario's !!

"simon" <simon_at_publishers-market.com> wrote in message news:BMIN7.2$WE4.2563_at_news.ecrc.de...
> Hi,
>
> If I make a ALTER SYSTEM ARCHIVE LOG CURRENT, then copy all archived logs
> to another machine with earlier copied datafiles/current redo logs, IN
> THEORY surely I should have enough redo to fully recover. In practice, I
> seem to be able to do this if I have the above plus:
>
> 1. a copy of a current control file (or a (binary) backup controlfile),
> Doesn't matter if I don't have current copies of redo logs because all the
> redo is in the archives.
>
> or
>
> 2. Copies of CURRENT redo logs and I rebuild control file from a trace
> control file. Oracle seems to get highest SCN from current logs when it
> rebuilds the control file, so it says 'aha, SCN in data files is below
that
> in the archived logs, recovery needed.'
>
> But f i don't have current redo logs and try rebuilding a control file
from
> a trace copy, I can't recover at all.
>
> In theory, it seems to me that all the redo required is in the archived
> logs, so I should be able to say 'rebuild a control file from the trace
> file, ignore the SCN in the 'old/invalid current redo log, but get the SCN
> from the archived redo logs, so that I can recover.
>
> Im new to Oracle - \would appreciate it if some DBA could point out error
> in my thinking.
> thanks
> Simon
> --
> Simon Hume
> Publishers Market AG
> Lindwurmstrasse 129a
> D-80337 München
>
Received on Fri Nov 30 2001 - 11:58:21 CST