Re: Q re command files for Oracle start/stop

"Gerald B. Rosenberg" <No_at_address.net> wrote in message
> > On the other hand, you don't say if you're running in archivelog mode or
not
> > (cold backups in archivelog mode are perfectly possible). If you are,
make
> > sure BackupExec is NOT backing up the online redo log components of your
> > database. If you aren't, then still make sure it isn't backing them
> > up -although in noarchivelog mode, it is much less serious an error to
back
> > them up than in archivelog.
> >
> > Get it wrong, and you really will be defying the odds.
> >
>
> Not sure I understand the exposure. I am running in noarchive mode and
> doing a full cold tape backup (nightly) of the closed database including
> all files in the <ORAHOME>/ORADATA/<SID> directory, which includes .CTL,
> .DBF, and .LOG files. I am also backing up various other .ORA files.

There is no exposure if you're not in archivelog mode, since any datafile corruption or loss would be resolved by simply restoring your entire last cold backup. You lose any transactions committed after the time of that backup, but that's presumably a risk and a loss you're happy to accept, otherwise you wouldn't have chosen to run in noarchivelog.

Exposure arises if you are in archivelog mode and backup the online logs. In archivelog mode, you expect to be able to perform a complete recovery, by restoring only the damaged datafile(s) from your last backup, and then rolling it forward in time by applying archives to it, thus enabling it to 'catch up' with where the rest of the database has gotten to. Eventually, you will need to apply redo which is contained within your *online* logs. No problem with that either. But if you've got backed up copies of the online logs in your backup set, there is a risk, shall we say a 'temptation', to restore them too -at which point, you'd have overwritten online logs that you need with copies which are out-of-date. That would prevent a complete recovery from succeeding, and you'd have just lost committed data.

Since successful complete recoveries *require* you never to use backup copies of your online logs, Oracle strongly recommends never to back them up in the first place. But this is strictly an archivelog mode issue: there's no harm in restoring backups of the online logs in noarchivelog mode since you can't do a complete recovery in that mode anyway.

I only mentioned it, because you didn't mention whether you were in archivelog mode or not.

> I have been able to transfer the database to another system with an
> otherwise identical installation of Oracle by restoring the backup'd
> files on the second system and then just starting the instance. That
> was (what I thought was) my proof that I was doing "the right thing."

And that's fine: you just missed out one vital piece of information from your original post, and I was covering all eventualities.

>
> What am I missing and what can I do to improve my odds?
>

Nothing. You're doing it just fine -assuming you are happy losing committed transactions at some point.

Regards
HJR
> Thanks again!
>
> --
> Gerald B. Rosenberg
Received on Sat Jan 18 2003 - 15:36:38 CST