Re: Oracle backups using Snapshot Technology

Hi Dianna,

in the company I worked for, we have used the "split-mirror" technology for db backup (datawarehouse env.) on SAN.
With this method you can use rman to backup db later from the split mirror but it is not a must. If you use rman to make a backup in this case you must have a recovery catalog. There is one pitfall related to cataloging this backup to recovery catalog...check on metalink I have forgot the note id. AFAIK, generally there are two methodologies available: triple mirroring and point-in-time snapshots both giving you the possibility to take a backup in a matter of second.

The disadvantage (if we assume your budget is not a problem) of both this method from my point of view is you need significant assistance of storage admin. on both backup and recovery and involving more people from different departments in case db recovery is needed. The relationship db admin - storage admin departments is not always a "love story" :-)

AFAIK, snapshots are commonly based on copy-on-write functionality...meaning original block is read and written to the snapshot destination before it is overwritten resulting in increasing number of writes impacting database performance.
Creating the db snapshot images you can do either on the storage array level or using oracle 10g flashback database option (software based approach).

There are different solutions available for both SAN and NAS. For SAN check on you SAN hardware vendor compatibility matrix for possible solutions and for NAS check the OSCP for certified NAS vendors and their solutions. I know that EMC Clarion have tool for taking snapshots...also check PolyServe, NetApp, they have products related to this topic too.

HTH,
goran

On 11/8/06, DIANNA GIBBS <DIANNA.GIBBS_at_childrens.com> wrote:
>
> We're looking at implementing a new enterprise backup solution.
>
> Is anyone using "snapshot technology" to backup your oracle databases?
> If so, could I get more info - O/S, database version, database size,
> timings for putting tablespaces in backup mode (database mode if 10g),
> SGA size, good things, lessons learned, comments or thoughts?
> Have you tested the backup, recovered or refreshed an environment using
> this technology - any issues?
>
> What about snapshot vs RMAN - any comments?
>
> Thanks in advance.
> Dianna Gibbs
> Children's Medical Center - Dallas
>
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> http://www.freelists.org/webpage/oracle-l
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