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Date: Wed, 6 Jun 2012 11:38:21 -0400
Message-ID: <CAJ7936xX=9p6mnnXRVS8dRDWaGchNd1ftjGwAE-ZX5MGTxuB7A@mail.gmail.com>
Subject: Re: VLDB ASM & SAN Striping Question
From: Matthew Zito <matt@crackpotideas.com>
To: ChrisDavid.Taylor@ingrambarge.com
Cc: "oracle-l@freelists.org" <oracle-l@freelists.org>
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Reply-To: matt@crackpotideas.com

I haven't poked around the EVA line in a while, but if I remember
correctly,what you describe is basically impossible in an EVA.  The
way an EVA works, you make a disk group, and all of the LUNs in that
disk group are dynamically striped across the disks in that group.
You could theoretically make a 2-disk group, and one LUN from those,
but I *think* you have to assign hot spares to individual disk groups,
and hence you'd burn a lot of storage just on spares in that
architecture.

What you could do is ask them to make sure that when you add a new
LUN, it comes from a different disk group than the current LUNs.
Probably your best bet.

Matt

On Wed, Jun 6, 2012 at 8:22 AM, Taylor, Chris David
<ChrisDavid.Taylor@ingrambarge.com> wrote:
> I am curious if anyone on this list has worked on disk striping at the SAN layer and then at the ASM layer?  Specifically, I want to know if you drilled all the way down to the physical devices on the SAN (controllers and physical disks) to make your hardware stripes?
> In the my current IT dept (and in my previous one) the SAN administrators weren't SAN experts (no fault of theirs) and I was told they couldn't stripe disk groups across specific controllers and specific disks (meaning they didn't know if it was possible and if it was they didn't know how to accomplish it).
>
> I was reading the Oracle doc "Oracle Database VLDB and Partitioning Guide 11g Release 2 (11.2) at: http://docs.oracle.com/cd/E11882_01/server.112/e16541/vldb_storage.htm when I saw this paragraph:
>
> "Oracle ASM can be used on top of previously striped storage devices. If you use such a configuration, then ensure that you do not introduce hot spots by defining disk groups that span logical devices which physically may be using the same resource (disk, controller, or channel to disk) rather than other available resources. Always ensure that Oracle ASM stripes are distributed equally across all physical devices."
>
> I understand striping really well.  What I'm having a hard time is finding the "how" in creating LUNS across specific controllers and only specific disks attached to those controllers in a typical SAN (specifically we're using an HP EVA 8100).  Who of you have actually done this - drill down to the controllers and devices and how hard was it to convince the SAN administrator to help accomplish this?
>
> Any input and thoughts are appreciated.
>
>
> Chris Taylor
>
> "Quality is never an accident; it is always the result of intelligent effort."
> -- John Ruskin (English Writer 1819-1900)
>
> Any views and/or opinions expressed herein are my own and do not necessarily reflect the views of Ingram Industries, its affiliates, its subsidiaries or its employees.
>
>
>
>
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