Re: Cold backup versus hot backup.

From: Tim Gorman <tim_at_evdbt.com>
Date: Mon, 13 Apr 2009 11:00:04 -0600
Message-ID: <49E36F94.4090203_at_evdbt.com>

Stop talking backups and start talking recovery/availability requirements. This is a case where the debate is incorrectly framed.

If you have an application which can be unavailable for regular periods at regular intervals, and which does not need to be recovered to the point-in-time of failure (assuming cold backups imply NOARCHIVELOG mode), then NOARCHIVELOG mode (which permits only cold backups) is a valid alternative.

However, if your application cannot be unavailable (down) for the period of time it takes to backup, or if there is a requirement that any failure be recovered to the point-in-time of failure, then it is extremely unlikely that anything but ARCHIVELOG mode and "hot" backups will work. Yes, I know some folks administering data warehouses who have implemented a "rebuild-then-reload" strategy and that works, but details like that should be included in the analysis of recovery requirements.

Still, running NOARCHIVELOG mode eliminates so many useful features, such as Log Miner, that it really rarely makes sense to even try it. The upshot is that you either have to be truly indifferent to all aspects of a database, or you have to be in such a crunch for I/O capacity that archiving redo log files is simply not possible (or both!), to run a database in NOARCHIVELOG mode.

Hope this helps....

Tim Gorman
consultant - Evergreen Database Technologies, Inc. P.O. Box 630791, Highlands Ranch CO 80163-0791

website   = http://www.EvDBT.com/
email     = Tim_at_EvDBT.com
mobile    = +1-303-885-4526
fax       = +1-303-484-3608
Yahoo IM  = tim_evdbt

Guillermo Alan Bort wrote:
> Another debate...
>
> We have several DBs that are currently under a cold backup schema.
> Basically they go down either every day or once a week and a full cold
> backup is taken. There are several issues related to the DB starting
> up before the backup ends, but that's not an Oracle problem, nor a
> cold-backup problem... just a lack of attention problem.
>
> On the other hand, hot backups have many advantages...
>
> what do you consider are the advantages and disadvantages of both cold
> and hot backups, and would you use a cold backup schema? if so, in
> what situation?
>
> Thanks ^_^
>
>
> Alan Bort
> Oracle Certified Professional
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>
>
>

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Received on Mon Apr 13 2009 - 12:00:04 CDT