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Re: Strategy question for 24X7, how to do cold backups?

From: Paul Drake <>
Date: Wed, 26 Sep 2001 06:44:17 GMT
Message-ID: <>

Galen Boyer wrote:
> All web clients want a 24X7 solution. Immediately, hot backups
> are needed. But, then, for a true 24X7, one must keep a copy of
> all of the redo logs from day one and a recovery would take quite
> awhile (Maybe I'm wrong here and the question is moot). On
> google, I am reading that one strategy is to configure a standby
> database where the current database's redo logs are applied
> against the standby. Then, if done correctly, a cold backup is
> never needed? Even if it is, the standby can be used to produce
> the cold backup?
> Am I on the correct path to the #1 solution for this and are
> there other options as well for actually achieving 24X7?
> Thanks.
> --
> Galen Boyer


If you do not have a cold backup prior to putting the database into production, you have committed a grave error. I suggest that you grab a the backup and recovery handbook (Velpuri) and the Oracle docs - Backup and recovery guide for your version - and do some heavy reading. The DBA checklists book (O'Reilly) has some good material on this subject.

The archived redo logs are only of use if you have copy of the datafiles to apply them to.
Yes, a *valid* hot backup set is as good as a cold backup set - once it has completed, provided that you have valid controlfiles.

As others have indicated, a full export (say weekly when the system load is low) is an essential part of an overall backup and recovery strategy, for recovery from human errors.

If you have tablespaces that contain read-only data - once the tablespace is altered to READ ONLY, you need back it up only once (and retain the datafiles) until the tablespace is altered to READ WRITE. The can greatly reduce the size of a backup set.

Ideally, you'd have a sufficient amount of free disk space such that the most recent copies of the datafiles from the hot backup job and all archived redo logs produced since the oldest backed up datafile would be on disk (*besides* being backed up to tape). If this is not possible, if you can spare the CPU cycles, a compressed set on disk is still better than restoring it from tape (though still not a replacement for copies on tape).

If you can afford the downtime window, I would:

run hot backups each night, every m,t,w,th,f run a cold backup (to disk) sunday morning around 3 am - not required, just doesn't hurt to have one.
run an export sunday evening.
groom the archived redo logs as required.

run the dbv.exe utility (if you're on win32) as part of your hot and cold backup jobs.

and - look into RMAN. I'm not using it yet, but the 9i version of it is sounding better and better.


Paul Received on Wed Sep 26 2001 - 01:44:17 CDT

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