RE: mirroring database storage

From: Martin Bach <>
Date: Fri, 24 Jun 2011 07:22:22 +0100
Message-ID: <003901cc3237$188289e0$49879da0$>

Hi Maureen,

Are you going to mirror those on the same or a different array? Mirroring on the same array might be a good idea for snapshots pre/post large batch processes to save on restore time. I have seen this used extensively and it's a good way to back out a release for a large database. Large in this context is any database which requires more time to restore than you have. You need to ensure though that you not only create a snapshot of the database, you also need a quick way to go back for any middle and client tier as well. Any existing replication should of course be stopped, especially Data Guard-if left active your primary and standby will be out of sync. Finally your system (storage) team should be comfortable with the procedure to get the whole environment back, should that be required it can get hectic!

But should you have a blackout on the data centre the mirror copy on the local array won't help you much....

It's a different story if you are remote-mirroring to a DR data centre. All storage vendors have a product available (SRDF, Continuous Access, etc) to replicate on the array level but with Data Guard in place that's money not worth investing in my opinion.

Best regards,


Martin Bach
Martin Bach Consulting Ltd

> -----Original Message-----
> From: []
> On Behalf Of Maureen English
> Sent: 23 June 2011 17:59
> Subject: mirroring database storage
> Does anyone use, or see any problems with, mirroring database files to
> provide a quick way to recover in case of a disk problem?
> We aren't yet using RAC, we do have a standby database set up at our
> disaster recovery site and we do weekly cold backups of the database.
> We're thinking that mirroring the database storage disks would be another
> layer of protection.
> Any comments?
> - Maureen
> --

Received on Fri Jun 24 2011 - 01:22:22 CDT

Original text of this message