From: Joshua D. Drake <jd@commandprompt.com>
To: William Yu <wyu@talisys.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Hardware/OS recommendations for large databases (
Date: Wed, 16 Nov 2005 08:03:37 -0800
Message-ID: <437B5859.9040805@commandprompt.com> (raw)
In-Reply-To: <dlfjgf$41b$1@news.hub.org>
References: <3E37B936B592014B978C4415F90D662D01995F7B@MI8NYCMAIL06.Mi8.com>
<33c6269f0511152115v1a34ab81j30f1f5df5a6c6956@mail.gmail.com>
<dlfjgf$41b$1@news.hub.org>
>
> The only questions would be:
> (1) Do you need a SMP server at all? I'd claim yes -- you always need
> 2+ cores whether it's DC or 2P to avoid IO interrupts blocking other
> processes from running.
I would back this up. Even for smaller installations (single raid 1, 1
gig of ram). Why? Well because many applications are going to be CPU
bound. For example
we have a PHP application that is a CMS. On a single CPU machine, RAID 1
it takes about 300ms to deliver a single page, point to point. We are
not IO bound.
So what happens is that under reasonable load we are actually waiting
for the CPU to process the code.
A simple upgrade to an SMP machine literally doubles our performance
because we are still not IO bound. I strongly suggest that everyone use
at least a single dual core because of this experience.
>
> (3) Do you need an insane amount of memory? Well here's the case where
> the more expensive motherboard will serve you better since each CPU
> slot has its own bank of memory. Spend more money on memory, get
> cheaper single-core CPUs.
Agreed. A lot of times the slowest dual-core is 5x what you actually
need. So get the slowest, and bulk up on memory. If nothing else memory
is cheap today and it might not be tomorrow.
> Of course, this doesn't apply if you are an Intel/Dell-only shop. Xeon
> DCs, while cheaper than their corresponding single-core SMPs, don't
> have the same performance profile of Opteron DCs. Basically, you're
> paying a bit extra so your server can generate a ton more heat.
>
Well if you are an Intel/Dell shop running PostgreSQL you have bigger
problems ;)
Sincerely,
Joshua D. Drake
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
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To: pgsql-performance@postgresql.org
Cc: jd@commandprompt.com, wyu@talisys.com
Subject: Re: Hardware/OS recommendations for large databases (
In-Reply-To: <437B5859.9040805@commandprompt.com>
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