Re: ASM mirroring vs SAM mirroring
- From: "Alex Gorbachev" <ag@xxxxxxxxxxxx>
- To: tony.van.esch@xxxxxxxxx
- Date: Sat, 28 Jul 2007 18:35:40 -0400
You can consider placing 3rd voting disk to NFS if it's available.
You can actually run cluster with two voting disks but reliability of
this solution is lower than with one. :)
Regarding ASM mirroring with two failure groups (i.e. across two
arrays) I have mentione the issue a while ago -
http://www.oracloid.com/2006/05/vldb-with-asm/. This seems to be
addressed in 11g with fast re-silvering but I didn't check it.
Also, you won't be able to make each node preferred reads from "local"
array so that it doesn't go to the "remote" storage box. I heard it's
possible in 11g but, again, I didn't check.
Just my two cents.
On 7/27/07, Tony van Esch <tony.van.esch@xxxxxxxxx> wrote:
> Hi Peter,
>
> In the EVA SAN there is always some kind of 'mirroring/redundancy' involved
> (VRAIDx), but not across storage boxes. Another interesseting point to
> consider is what to do with the voting disk(s). You need an uneven amount of
> votingdisks to run a cluster. If you use 1 vote, this is a Single Point Of
> Failure. Next up is a three vote config, but then you need some kind of
> independent third storage unit separate from the two EVA's.
>
> Regards,
> Tony van Esch
>
--
Alex Gorbachev, Oracle DBA Brewer, The Pythian Group
http://www.pythian.com/blogs/author/alex http://www.oracloid.com
BAAG party - www.BattleAgainstAnyGuess.com
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