Re: VLDB ASM & SAN Striping Question
- From: Matthew Zito <matt@xxxxxxxxxxxxxxxxx>
- To: ChrisDavid.Taylor@xxxxxxxxxxxxxxx
- Date: Wed, 6 Jun 2012 11:38:21 -0400
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@xxxxxxxxxxxxxxx> 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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