From: Jim C. Nasby <decibel@decibel.org>
To: Hannes Dorbath <light@theendofthetunnel.de>
Cc: Gregory Stark <stark@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: FORGOT TO CONFIGURE RAID! DELL POWEREDGE 2950
Date: Mon, 16 Jul 2007 16:02:11 -0500
Message-ID: <20070716210210.GZ39272@nasby.net> (raw)
In-Reply-To: <4698A347.2020401@theendofthetunnel.de>
References: <1184357777.135345.38110@n60g2000hse.googlegroups.com>
<46988951.9050108@theendofthetunnel.de>
<87tzs7b93w.fsf@oxford.xeocode.com>
<4698A347.2020401@theendofthetunnel.de>
On Sat, Jul 14, 2007 at 12:19:51PM +0200, Hannes Dorbath wrote:
> 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.
Wow, are you sure about that? I've never heard it before, but that'd be
pretty disturbing if it's true...
--
Jim Nasby decibel@decibel.org
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: decibel@decibel.org, light@theendofthetunnel.de, stark@enterprisedb.com
Subject: Re: FORGOT TO CONFIGURE RAID! DELL POWEREDGE 2950
In-Reply-To: <20070716210210.GZ39272@nasby.net>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox