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RE: ASM questions

From: Matthew Zito <>
Date: Wed, 13 Jun 2007 13:19:55 -0400
Message-ID: <>

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.  


[] On Behalf Of Best, David

	Sent: Wednesday, June 13, 2007 12:06 PM
	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?


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Received on Wed Jun 13 2007 - 12:19:55 CDT

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