Re: EMC Snapshot Technology

Clariion snapshots are useful for point-in-time copies and remote replication. However, they are in no way a solution for full backups, as on a snapshot, the new snapshot volume that is created lives on the same physical disks as the original volume. Sooo, if you have a RAID set failure on a volume, all the snapshots associated with it are gone as well. This differs from third-mirror point-in-time copies like BCVs, where there is an actual extra set of spindles for the RAID group.

The other big downside about snapshots is that if you're using them to back up to tape, all your i/o goes to the same physical disks are your still-active production database. So, the heavy read i/o can negatively impact throughput to production.

Also, one note about RAC on EMC - be very careful to match your configuration to one of EMC's certified configs, as they will refuse to support you if things don't match (this includes down to oracle patch rev - 9.2.0.4 is not yet supported on most configs, for example).

Thanks,
Matt

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, October 08, 2003 9:39 PM

> We are implementing Oracle RAC on two Windows nodes, connected to an EMC
> SAN. We'll also have a failover sight.
>
> We are using S.A.M.E. disk configuration, with only one logical volume,
> and backups/archivelogs dumping to another volume.
>
> The SAN is an EMC Clariion CX400.
>
> I immediately vetoed snapshots, opting for RMAN, but I'm now taking a
> second look.
>
> Does anyone use the snapshot technology as a solution for full backups?
>
> Thanks,
>
> Jeff
>
>
>
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Matthew Zito
  INET: mzito_at_gridapp.com

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