Re: ASM questions

That sounds like a classic case for flashback database in my book, most dev environments I've seen would never want to go back far, since dev is production for the developers, but might want to reverse out errors/blind alleys and so on.

Niall

On 6/14/07, Best, David <David.Best_at_cognos.com> wrote:
>
>
> Thanks for the reponses, I should clarify that we wouldn't be using BCV's
> for production. Its just for our testing enviornment in case we need to
> switch back quickly to a previous backup.
>
> ------------------------------
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Randy Johnson
> *Sent:* Thursday, June 14, 2007 1:15 AM
> *To:* oracle-l_at_freelists.org
> *Subject:* RE: ASM questions
>
>
> [You're probably better off using RMAN, flashback, data guard, etc. - so
> much more fine-grained than BCVs.]
>
> I agree with Matt on this. I've been doing ASM with RMAN for a year now
> and you will be severly limiting your recovery options if you stray from
> RMAN for your backups. Just to list a few not too obvious advantages:
>
> -Block level recovery. One bad block in your database? Just recover
> that block not the whole file or database.
> -Database Cloning
> -Every block is verified during backup and during restore.
> -Block change tracking makes incremental backups very fast.
> -Recovery auditing using "restore database validate check logical"
>
> Hope this helps...
>
> -Randy
>
>
>
> ------------------------------
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Matthew Zito
> *Sent:* Wednesday, June 13, 2007 12:20 PM
> *To:* David.Best_at_cognos.com; oracle-l_at_freelists.org
> *Subject:* RE: ASM questions
>
>
> You probably want to be careful using BCVs in an ASM environment. First,
> depending on your platform and configuration, you may be using disk
> signatures to identify the disks, and should you reboot a node while the
> BCVs are split (assuming they're exposed to one of the nodes in the
> cluster), the node will see two different disks with the same ID, and could
> be fairly unhappy about it. The other thing to make sure is that you do an
> "instant split" on the BCVs, so they're consistent. And also, you would
> want to put your archive logs in a different ASM diskgroup than the BCV one,
> so that in a restore situation you don't overwrite your archive logs during
> the restore.
>
> Also, with ASM there are no "mount points" - to the OS, they look just
> like raw disks. Assuming this is an EMC environment (and you're not using
> the BCV term generically), though, when you do a BCV restore, nothing will
> change about the disks. Basically you would bring the ASM instances down, do
> a bcv restore (at a Symmetrix level), and then start ASM back up. Poof -
> rolled back to the previous copy.
>
> However, BCVs are a pretty crude tool these days for backup and recovery
> situations - you can only have one or two copies, it burns a bunch of space
> on your Symm as a third/fourth mirror, and there's no incremental
> intelligence (you do get a slight read performance bump when your BCVs are
> in established mode, but I know few people that care _that_ much about
> that). You're probably better off using RMAN, flashback, data guard, etc. -
> so much more fine-grained than BCVs.
>
> Matt
>
>
> ------------------------------
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Best, David
> *Sent:* Wednesday, June 13, 2007 12:06 PM
> *To:* oracle-l_at_freelists.org
> *Subject:* ASM questions
>
>
>
> Hey all,
>
> Please forgive my ASM ignorance if it shows but I have a couple of
> questions. We are considering using BCV Copy with an ASM environment (the
> database is RAC'd if that matters).
>
> Once we make a BCV copy, what is the quickest way to restore?
>
> I would assume the easiest would be to replace the volumes with the BCV
> copy, thus keeping the device names, mount points the same. Then you would
> just perform a database recovery.
>
> What if you mounted the BCV copy on the server, so in that case the mount
> point, device name, etc are different? Can you recreate diskgroups in ASM
> after they have been initially created so they point to the new location?
>
> Thanks
>
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-- 
Niall Litchfield
Oracle DBA
http://www.orawin.info

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