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Re: datafiles and tempfiles

From: Daniel Morgan <>
Date: Tue, 02 Jul 2002 19:47:21 GMT
Message-ID: <>

Sean M wrote:

> Chuck wrote:
> >
> > Yes I back up online logs too. I do it for two reasons
> >
> > 1. It simplifies the restore script. I just run a tar -xvf filename and I am
> > done. No additional steps of resetting logs or recreating tablespaces after
> > restarting the database.
> Are you running in archivelog mode? If so, Oracle does NOT recommend
> backing up your online redo logs, hot or cold. I would argue that you
> should not get in the habit of backing up online redo logs regardless of
> whether you are in archivelog mode or not. You NEVER require backups of
> them for recovery, and the habit can seriously burn you if your database
> is in archivelog mode.
> > 2. It's what oracle explicitly states to do for a cold backup in their
> > documentation. See metalink note # 97495.1 updated last on 10-Jun-2002.
> > Though this document is geared for NT the principles of a cold backup are
> > the same. It clearly says to backup *all* database files (I take that to
> > mean tempfiles and datafiles since they are both part of the database), and
> > all online redo log files. There are a host of othe metalink documents that
> > deal with cold backups and all of them say the same thing. Get all database
> > files and online redo logs. It makes the recovery simpler.
> True, it simplifies recovery for databases in NOARCHIVELOG mode (though
> I hardly consider adding the word RESETLOGS to your "alter database
> open" command and adding in a tempfile or two to be complex). It can
> (will) cause serious problems for databases in ARCHIVELOG mode. Nothing
> in the note you referenced specifically states that the database is in
> ARCHIVELOG mode, so technically it is OK (though I still say it's a bad
> habit). But I would strongly encourage you to not follow the
> instructions in the Metalink note for an ARCHIVELOG database.
> Futhermore, that note was originally written for 8.0, before the advent
> of tempfiles. The script included does NOT back them up (it only
> selects from v$datafile). Also note the disclaimer "The sample program
> in this article is provided for educational purposes only. It is NOT
> supported by Oracle Support Services."
> I'd be surprised if you could produce a Metalink document that advocates
> 1) backing up online redo logs explicity for archivelog mode databases
> or 2) explicit references to backing up a tempfile.
> Regards,
> Sean

And, I might add, if it is a production database and is not in ARCHIVELOG mode exactly what is the value of the transaction being processed? Apparently zero. Apparently you it is ok to lose the last eleven hours of transactions as long as you have the last fifteen minutes.

Daniel Morgan Received on Tue Jul 02 2002 - 14:47:21 CDT

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