RE: More than 2 ASM Diskgroups in a RAC Enviornment with 2 Databases
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <naqimirza@xxxxxxxxx>, "'K Gopalakrishnan'" <kaygopal@xxxxxxxxx>, "'Oracle-l List'" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 9 Mar 2007 13:07:46 -0500
Let me take a quick run at this. We have a bit of a language problem
regarding the word "general." In science, a general theory must apply to
all cases. In the vernacular about "best practices" and otherwise you will
find the word "general" used in a way that means "the commonly found special
case."
Here are a few things off the top of my head that are characteristics of the
commonly found special case I hope Oracle refers to:
1) The disks/disk arrays you have operate at the same speed.
2) No database or process loads exist that you must protect from each
other.
3) The disks/disk arrays you have are uniform in need for ASM to
provide or not provide additional redundancy.
These issues have little or nothing to do with size. There might also be
reasons to have more disk groups simply to group them by some maximum size,
but I find as things get huge you reach reasons to be a little more
sophisticated in the disk group construction so I have not hit any size
limits.
I believe the best practice described in this case is intended to give you a
minimized initial construction cost and balance in load across the disk
farm.
I posted something a bit longer a while ago that some folks thought was a
useful summary of the cases, and if you want to consider things in depth
beyond that I think Morle's stuff about Sane SAN is useful next step. If a
simple flat profile is all you need, then SAME in the two described bits is
a simple baseline to implement.
But please don't confuse balance with optimal.
mwf
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Naqi Mirza
Sent: Friday, March 09, 2007 2:06 AM
To: K Gopalakrishnan; Oracle-l List
Cc: racdba@xxxxxxxxxxxxx
Subject: Re: More than 2 ASM Diskgroups in a RAC Enviornment with 2
Databases
Gopal,
This is from the the ASM Best Practices Document on OTN. See page 12 of 39,
under diskgroups and databases:
.
To reduce the complexity of managing asm and its diskgroups, Oracle
Recommends that generally no more than two diskgroups be maintained and
managed per RAC cluster or single ASM Instance.
.
That said, I didn't mean to imply its not supported or not possible - I,
only, inferred this from the above.
That said, I proceeded to test the install, with the details below - and its
all good - works fine (so far).
Thanks
Naqi
----- Original Message ----
From: K Gopalakrishnan <kaygopal@xxxxxxxxx>
To: naqimirza@xxxxxxxxx; Oracle-l List <oracle-l@xxxxxxxxxxxxx>
Cc: racdba@xxxxxxxxxxxxx
Sent: Thursday, 8 March, 2007 9:12:52 PM
Subject: Re: More than 2 ASM Diskgroups in a RAC Enviornment with 2
Databases
Naqi,
Which document you are talking about? We never say 'no more than 2
disk groups per cluster'.
Btw your initial plan seems perfect.
-Gopal
On 3/7/07, Naqi Mirza <naqimirza@xxxxxxxxx> wrote:
>
> I see a similar question to this has already been posted, but just
wondering
> if anyone's actually had to configure something like this before.
>
>
>
>
> ----- Original Message ----
> From: Naqi Mirza <naqimirza@xxxxxxxxx>
> To: oracle-l <oracle-l@xxxxxxxxxxxxx>
> Sent: Wednesday, 7 March, 2007 2:07:47 PM
> Subject: More than 2 ASM Diskgroups in a RAC Enviornment with 2 Databases
>
> Hi,
>
> ---- Start ----
> Config Details:
>
> 2 Node 10gR2 RAC
> HP-UX (PA-RISC) 64 Bit, 11.23
> Serviceguard 11.17
> ASM used as storage option for database and recovery files.
>
> ---- End ----
>
> This 2 node cluster will host 2 RAC databases. Looking at the best
practices
> document for ASM, I see it says that typically you should have no more
than
> 2 diskgroups per RAC cluster.
> However, the initial plan was to create 4 diskgroups - 2 for each
database.
> Just wondering if anyone has done something similar to this, or if anyone
> has more than 1 rac database using asm as the storage?
>
> Thanks
>
> Naqi
>
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--
Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/
Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/
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