Message-ID: <437DE960.9070606@rentec.com>
Date: Fri, 18 Nov 2005 09:46:56 -0500
From: Alan Stange <stange@rentec.com>
Reply-To: stange@rentec.com
Organization: Renaissance Technologies Corp.
User-Agent: Thunderbird 1.5 (X11/20051025)
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To: Luke Lonergan <llonergan@greenplum.com>
CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>,
	Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Hardware/OS recommendations for large databases (
References: <BFA31B52.14012%llonergan@greenplum.com>
In-Reply-To: <BFA31B52.14012%llonergan@greenplum.com>
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Luke Lonergan wrote:
> Alan,
>
> On 11/18/05 5:41 AM, "Alan Stange" <stange@rentec.com> wrote:
>
>   
>> That's interesting, as I occasionally see more than 110MB/s of
>> postgresql IO on our system.  I'm using a 32KB block size, which has
>> been a huge win in performance for our usage patterns.   300GB database
>> with a lot of turnover.  A vacuum analyze now takes about 3 hours, which
>> is much shorter than before.  Postgresql 8.1, dual opteron, 8GB memory,
>> Linux 2.6.11, FC drives.
>>     
>
> 300GB / 3 hours = 27MB/s.
>   
That's 3 hours under load, with 80 compute clients beating on the 
database at the same time.   We have the stats turned way up, so the 
analyze tends to read a big chunk of the tables a second time as 
well.    We typically don't have three hours a day of idle time.

-- Alan