Re: Purchasing the correct hardware: dual-core intel? Big cache?

On Mon, 24 Apr 2006 18:31:46 -0500
Derek Ragona <derek@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:

You can get better information directly from intel's website on
motherboards and CPU performance. Dual core is faster than hyperthreaded
CPU's usually about 20% if you use the larger CPU cache models.

I don't follow you here. Are you saying that dual core is about
20% faster than hyperthreaded with larger cache?

However with a RDBMS as the primary usage, I would look for more ways to
optimize the system. I would look to use a RAID array with an add-on card
(or zero-chanel add-on) as this will provide better performance (with a
raid 0) or better performance with redundancy (raid 10, or RAID 0+1.) A
RAID adapter will offload the DISK I/O providing substantially better
performance.

We are using Dell PERC controllers with SCSI 320 disks in a RAID-10
configuration, and battery-backed cache. As a result, disk IO is _not_
a bottleneck. All of our tests up till now have demonstrated that
memory and disk usage are minimal, and that CPU usage is the current
bottleneck.

At 02:46 PM 4/24/2006, you wrote:

I've been asked to make some hardware recommendations, I'm hoping some
folks on the list can make some suggestions.

We're looking hard at getting either Intel dual-core procs, or getting
hyperthreaded procs with huge (8M) caches.

We currently have a few dual proc Intel HT machines that we can test
out our workload on, and I'm trying to get a feel for how to determine
if a larger cache size will generate better performance than replacing
HT procs with full-blown dual-core procs. We're looking at the 6850
from Dell, which supports both processor families:
http://www1.us.dell.com/content/products/productdetails.aspx/pedge_6850?c=us&cs=555&l=en&s=biz

The goal for these machines is to serve out PosgreSQL databases to as
many Apache+php front ends as we can hang off each one. So we're trying
to purchase hardware that will create a DB server that can handle a lot
of web server front ends.

I have a Dell 2850 (dual HT procs) here that I can use for testing.
I'm a little fuzzy on determining how well the cache is working, so I'm
stuck on whether or not the 8M cache that's available on the HT units
is worth the money or not. Can anyone suggest a testing methodology
that will isolate this particular aspect?

--
Bill Moran
Collaborative Fusion Inc.
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--
Bill Moran
Collaborative Fusion Inc.

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