From: Hannes Dorbath <light@theendofthetunnel.de>
Subject: Re: FORGOT TO CONFIGURE RAID!       DELL POWEREDGE 2950
Date: Sat, 14 Jul 2007 12:19:51 +0200
Organization: Hub.Org Networking Services
Lines: 21
Message-ID: <4698A347.2020401@theendofthetunnel.de>
References: <1184357777.135345.38110@n60g2000hse.googlegroups.com>
	<46988951.9050108@theendofthetunnel.de>
	<87tzs7b93w.fsf@oxford.xeocode.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
To: Gregory Stark <stark@enterprisedb.com>
User-Agent: Thunderbird 2.0.0.4 (Windows/20070604)
In-Reply-To: <87tzs7b93w.fsf@oxford.xeocode.com>
To: pgsql-performance@postgresql.org

Gregory Stark wrote:
>> From the DELL site it seems this `PERC 5/i' on board controller
>> (assuming that's what you have) doesn't even have a BBU. If you don't
>> plan to post here in a few weeks again about data corruption, go out and
>> shop a serious controller.
> 
> This is a bit of a strange comment. A BBU will improve performance but
> Postgres doesn't require one to guarantee data integrity.
> 
> If your drives have write caching disabled (ie write-through) and your
> controller does write-through caching and you leave fsync=on and
> full_page_writes=on which is the default then you shouldn't have any data
> integrity issues.

That was my point, controllers without BBU usually leave drive caches
turned on, as with drive caches off performance would be unbearable bad.


-- 
Best regards,
Hannes Dorbath