X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id B64B7D726E for ; Wed, 24 Aug 2005 12:52:12 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 11324-06 for ; Wed, 24 Aug 2005 15:52:07 +0000 (GMT) Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) by svr1.postgresql.org (Postfix) with ESMTP id 6A1BFD7166 for ; Wed, 24 Aug 2005 12:52:06 -0300 (ADT) Received: from kungfu (frank.wiles.org [127.0.0.1]) by frank.wiles.org (8.13.1/8.13.1) with SMTP id j7OF0ljd015554; Wed, 24 Aug 2005 10:00:47 -0500 Date: Wed, 24 Aug 2005 10:52:43 -0500 From: Frank Wiles To: Alexandre Barros Cc: pgsql-performance@postgresql.org Subject: Re: performance drop on RAID5 Message-Id: <20050824105243.067f0ae5.frank@wiles.org> In-Reply-To: <430C8779.9080500@vectorx.com.br> References: <430C8779.9080500@vectorx.com.br> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0 required=5 tests=[none] X-Spam-Level: X-Archive-Number: 200508/384 X-Sequence-Number: 14131 On Wed, 24 Aug 2005 11:43:05 -0300 Alexandre Barros wrote: > I've googled a little, and maybe the cluster size might be one > problem, but despite that, the performance dropping when running on > "server-class" hardware with RAID-5 SCSI-2 drives was way above my > most delirious expectations... i need some help to figure out what is > **so** wrong... RAID-5 isn't great for databases in general. What would be better would be to mirror the disks to redundancy or do RAID 1+0. You could probably also increase your shared_buffers some, but that alone most likely won't make up your speed difference. --------------------------------- Frank Wiles http://www.wiles.org ---------------------------------