RE: RMAN question

From: Mercadante, Thomas F \(LABOR\) <Thomas.Mercadante_at_labor.state.ny.us>
Date: Wed, 28 Jun 2006 08:20:42 -0400
Message-ID: <ABB9D76E187C5146AB5683F5A07336FF681363@EXCNYSM0A1AJ.nysemail.nyenet>

Niall,

This makes no sense to me. What does a resync buy you? Does the resync register within Rman that new archivelog files are ready to be backed up? I don't think so but things change to freekin fast who the heck knows.

I always thought a resync would update the rman repository with physical database changes like adding any new data files to the system.

I just looked at rman docs. There is a view called rc_resync. In my catalog, there is an entry in this view when a database backup is taken. An Archivelog backup gets a status of "PARTIAL" while a full database backup gets a "FULL" resync_type when it needs one. It looks like rman performs a resync test every time it runs (and I seem to remember reading that this was a new feature in 9i).

So no, I do not resync the database on a regular basis (Oracle 9i). I perform a resync when I need to (like when I apply the quarterly security patches).

Hope this helps.

Tom

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-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Niall Litchfield Sent: Wednesday, June 28, 2006 6:21 AM
To: oracle-l
Subject: RMAN question

I'm after opinions and others practice.

At my new site we use RMAN with a catalog, at least some databases do and some didn't. I'm trying to ensure that what and how we backup is policy driven and consistent, primarily so that the recovery and cloning processes are consistent and predictable.

I therefore configured one of our new systems to use RMAN and register its backups with the catalog. Since this system is temporarily extremely short of disk space (and we don't have a media manager) I schedule a deletion of the old backup immediately before I take the new one, which in turn is scheduled just before the tape backup of the server - not great but there you go. Now as RMAN won't know that my nasty little cron has come along and deleted the backup from disk I run a crosscheck backup; delete expired after the new backup has been taken to resync the catalog.

It was suggested to me that best practice was to resync regularly (like every 15 minutes). I've read the docs and they sort of back me up (sorry for the pun!) in that they say that a manual resync is rarely required, but then rather drop themselves in it by suggesting that if you backup 'infrequently' where frequency is defined in terms of log switches not time then because the controlfile doesn't know about archivelogs generated since the last backup you should resync manually between backups. It seems to me that if there is any truth in this last then you should resync after every log switch, but my question is what do others do, and if you have a coherent reason so much the better!

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Niall Litchfield
Oracle DBA
http://www.orawin.info
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http://www.freelists.org/webpage/oracle-l Received on Wed Jun 28 2006 - 07:20:42 CDT