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Re: backup and recovery procedures / resetlog

From: Sean M <>
Date: Tue, 02 Jul 2002 13:54:34 -0600
Message-ID: <>

Bruno Jargot wrote:
> I'm currently writing procedures for the backup and recovery of
> databases.
> I read carefully the excellent paper of Howard J. Rogers but I've some
> questions.
> 1- Before doing a incomplete recovery, Howard strongly recommends a
> backup in order to be able to redo the recovery if necessary.
> I don't understand why I could not redo the recovery.
> I've a backup control file (trace) with each backup. If I want to redo
> the recovery, I should be able to use the backup control file and play
> again each archivelog until the resetlog. No ?
> If I do a backup of only the redolog files before the resetlog, I
> should have no loss. No ?
> If I don't backup the Control Files before the resetlogs, what are the
> consequence for a incomplete recovery (except the need of using the
> backup controlfiles) ?

You may find this (very recent) sub-thread useful:*

> 2- After a resetlog, Howard recommends to do a *cold* backup. A hot
> backup is not sufficient ? Why ?

A hot backup is ALWAYS sufficient, as long as you have the necessary archives for recovery. I believe Howards caution against this practice is that a hotbackup implies that users are accessing the database. Since (for all supported intents and purposes) you can't recover the database until you have a full backup after a resetlogs, if you were to have a failure before your hotbackup completes, you'd lose the new user data. A cold backup after a resetlogs effectively guarantees that no users touch the database until you have a full backup. You could just as easily do a startup restrict (locking out non-dba users), take a full hot backup, then open the database for full use. But why bother? So it's not so much hot or cold, but whether you have a full backup post-resetlogs before you release the database to users.

Sean M Received on Tue Jul 02 2002 - 14:54:34 CDT

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