DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta;
	h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding:sender;
	b=AvC2YNmUDFcFCzfNBjdhMWdgs+DpmaJ8OKg/3u952qHjg0n6DKgHkzEA5OCH9RN1PuvYUA74pRtyxCDrSJIkq5bstc1Us7Wi+6SqgF4LOARcXKmav/QnrWmnGIYvXo5xNK9VSVRgaULGdGUju9QiJsv6SqgDHiydZuDWXtNUVDs=
Message-ID: <4614C13C.6060107@enterprisedb.com>
Date: Thu, 05 Apr 2007 10:28:28 +0100
From: Heikki Linnakangas <heikki@enterprisedb.com>
User-Agent: Icedove 1.5.0.8 (X11/20061116)
MIME-Version: 1.0
To: jason@ohloh.net
CC: pgsql-performance@postgresql.org
Subject: Re: SCSI vs SATA
References: <200704042027.l34KRMI03358@momjian.us>
	<46140B49.3060205@commandprompt.com> <46140F05.9090403@mochima.com>
	<649E6F5F-13D0-4D2F-A842-722320FF8F3C@ohloh.net>
In-Reply-To: <649E6F5F-13D0-4D2F-A842-722320FF8F3C@ohloh.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

jason@ohloh.net wrote:
> In a perhaps fitting compromise, I have decide to go with a hybrid 
> solution:
> 
> 8*73GB 15k SAS drives hooked up to Adaptec 4800SAS
> PLUS
> 6*150GB SATA II drives hooked up to mobo (for now)
> 
> All wrapped in a 16bay 3U server. My reasoning is that the extra SATA 
> drives are practically free compared to the rest of the system (since 
> the mobo has 6 onboard connectors). I plan on putting the pg_xlog & 
> operating system on the sata drives and the tables/indices on the SAS 
> drives, although  I might not use the sata drives for the xlog if they 
> dont pan out perf-wise. I plan on getting the battery backed module for 
> the adaptec (72 hours of charge time).

If you have an OLTP kind of workload, you'll want to have the xlog on 
the drives with the battery backup module. The xlog needs to be fsync'd 
every time you commit, and the battery backup will effectively eliminate 
the delay that causes.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com