X-Original-To: pgsql-general-postgresql.org@localhost.postgresql.org Received: from localhost (mx1.hub.org [200.46.208.251]) by postgresql.org (Postfix) with ESMTP id 13D499F9F3D; Tue, 9 May 2006 08:36:09 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.208.251]) (amavisd-new, port 10024) with ESMTP id 42048-08; Tue, 9 May 2006 08:36:03 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from p0f.net (p0f.net [193.77.154.190]) by postgresql.org (Postfix) with ESMTP id 34F409F931D; Tue, 9 May 2006 08:36:03 -0300 (ADT) Received: from [10.10.190.53] ([193.77.165.58]) (authenticated bits=0) by p0f.net (8.13.3/8.13.3) with ESMTP id k49AqZgV002246 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 9 May 2006 12:52:38 +0200 Message-ID: <44607EDF.60109@p0f.net> Date: Tue, 09 May 2006 13:37:03 +0200 From: Grega Bremec Organization: P0F User-Agent: Mozilla Thunderbird 1.0 (X11/20041207) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Hannes Dorbath CC: pgsql-general@postgresql.org, pgsql-performance@postgresql.org Subject: Re: [PERFORM] Arguments Pro/Contra Software Raid References: In-Reply-To: X-Enigmail-Version: 0.93.0.0 OpenPGP: id=E077F97A Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200605/334 X-Sequence-Number: 95126 -----BEGIN PGP SIGNED MESSAGE----- Hash: RIPEMD160 Hannes Dorbath wrote: > Hi, > > I've just had some discussion with colleagues regarding the usage of > hardware or software raid 1/10 for our linux based database servers. > > I myself can't see much reason to spend $500 on high end controller > cards for a simple Raid 1. > > Any arguments pro or contra would be desirable. > One pro and one con off the top of my head. Hotplug. Depending on your platform, SATA may or may not be hotpluggable (I know AHCI mode is the only one promising some kind of a hotplug, which means ICH6+ and Silicon Image controllers last I heard). SCSI isn't hotpluggable without the use of special hotplug backplanes and disks. You lose that in software RAID, which effectively means you need to shut the box down and do maintenance. Hassle. CPU. It's cheap. Much cheaper than your average hardware RAID card. For the 5-10% overhead usually imposed by software RAID, you can throw in a faster CPU and never even notice it. Most cases aren't CPU-bound anyways, or at least, most cases are I/O bound for the better part. This does raise the question of I/O bandwidth your standard SATA or SCSI controller comes with, though. If you're careful about that and handle hotplug sufficiently, you're probably never going to notice you're not running on metal. Kind regards, - -- Grega Bremec gregab at p0f dot net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFEYHRAfu4IwuB3+XoRA9jqAJ9sS3RBJZEurvwUXGKrFMRZfYy9pQCggGHh tLAy/YtHwKvhd3ekVDGFtWE= =vlyC -----END PGP SIGNATURE-----