Re: Replicated File System Consistency
From: DA Morgan <damorgan_at_psoug.org>
Date: Fri, 02 Jan 2009 14:19:18 -0800
Message-ID: <1230934756.572394_at_bubbleator.drizzle.com>
Pat wrote:
>
> 8G cache on each head unit (2 head units), but I don't know how its
> configured. Frankly didn't even realize you could configure different
> read/write percentages. I supect the SAN guys know though; is it worth
> asking? Is there a recommendation as to how the cache should be
> allocated? Our workload is very read heavy so I'd naively assume a
> bigger read cache would be preferable.
>
> 30 Fiber Channel 15k drives on each of the main data aggregates.
>
> All the numbers point to the SAN being much faster, but I think
> what we basically proved is that we don't have an IO bound workload.
Date: Fri, 02 Jan 2009 14:19:18 -0800
Message-ID: <1230934756.572394_at_bubbleator.drizzle.com>
Pat wrote:
>> 4. How is the cache configured? What percentage read? What percentage write?
>
> 8G cache on each head unit (2 head units), but I don't know how its
> configured. Frankly didn't even realize you could configure different
> read/write percentages. I supect the SAN guys know though; is it worth
> asking? Is there a recommendation as to how the cache should be
> allocated? Our workload is very read heavy so I'd naively assume a
> bigger read cache would be preferable.
Configure 100% as read cache. Then test.
>> 5. How many physical disks are you striped over for your hottest data files?
>
> 30 Fiber Channel 15k drives on each of the main data aggregates.
>
> All the numbers point to the SAN being much faster, but I think
> what we basically proved is that we don't have an IO bound workload.
That is certainly what it sounds like.
> FWIW the main reason we went SAN wasn't throughput, but crash
> recovery. If a DB server explodes, I can mount its 3 LUNS on a hot
> spare and have it back up in a matter of minutes. Since nobody wanted
> to pay for dataguard, its the best hot failover strategy we could come
> up with.
Data Guard, assuming you have Enterprise Edition, is free. <g>
-- Daniel A. Morgan Oracle Ace Director & Instructor University of Washington damorgan_at_x.washington.edu (replace x with u to respond) Puget Sound Oracle Users Group www.psoug.orgReceived on Fri Jan 02 2009 - 16:19:18 CST