Re: SAN's, snapshots and online backups questions...

Where I work they're implementing a NAS storage strategy and I'be been involved in placing the Oracle datafiles on it. I was wary but all the tests I've done show it to be okay so far. You can indeed take backups in 15 seconds if that is important to you. (Personally, I don't think it's important.)

I just use old fashioned media backup and recovery techniques - no RMAN. In fact I think you need to use this approach since you will always be doing OS backups.

Simply replace your cp/ocopy, or whatever you use, to copy the files in your existing hot backup script with a call to the snapshot. Obviously you need to put all tablespaces in hot backup mode at the same time.

You will certainly need to do a lot of testing yourself and it won't necessarily simplify your backup approach.

Since your snap restores (volume or file) are just like restoring a file you will use exactly the same recovery techniques you have always used.

My vendor also has a technique called snap mirroring which updates blocks remotely to another site *while the database is in use and not in hot backup mode*. I am sceptical of this approach. However, I know the snapshots approach is sound and I will always be able to recover back to the last archived log at a secondary site.

It would be interesting to find out if people who have implemented SAN/NAS really think they are worth it. (Obviously if you're using RAC then you need SAN). I think the NAS technology is all very nice but to have just spent the money on lots of spare disks to write hot backups to would have suited me. Is looking after your RAID configuration such a chore? The NAS selling point is all about ROI, cost of ownership, etc.

And in the end - all backups go to tape at some stage!

Daniel.

On Fri, 18 Jul 2003 18:31:44 GMT, Glen A Stromquist <glen_stromquist_at_no.spam.yahoo.com> wrote:

>Our network admin is looking at various SAN strategy/solutions to
>implement for our storage need. I think that part of the sales pitch he
>has been getting is that the "snapshot" technology they employ
>eliminates the need for any existing oracle backup strategies. I won't
>go in to much detail, but I'm hearing things like how they can stop a
>(data)file from being written to whilst a snapshot is taken, putting the
>entire database into backup mode then doing a snapshot, how user
>response is "less affected" during backup times etc..
>
>I have no intention of changing my current online OS backups, as they
>are tried, tested & true and have minimal, if any impact on users.
>(other than changing over to Rman once I get more used to it) I did say
>that if there is no performance impact it may be a good enhancement to
>my current backup strategy however. But I am curious if anyone else has
>used this method for cloning etc.. and I am curious if indeed these
>snapshots do work, how can they be rolled forward once restored, if at all?
>
>I am sitting in on a meeting with another SAN vendor next week, and one
>of their reps is a very knowlegeable oracle person, so I expect to get
>some clarity on this issue then, but in the meantime thought some here
>might like to shed some light or share some experiences in this area.
>
>TIA
Received on Fri Jul 18 2003 - 16:19:54 CDT