Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 8F8CD65036B for ; Fri, 5 Dec 2008 19:30:07 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 18738-02 for ; Fri, 5 Dec 2008 19:30:05 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from skynet.simkin.ca (skynet.simkin.ca [72.51.27.117]) by mail.postgresql.org (Postfix) with ESMTP id 1AA6E64FC71 for ; Fri, 5 Dec 2008 19:30:04 -0400 (AST) Received: from charon.medialogik.com (unknown [10.10.2.229]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by skynet.simkin.ca (Postfix) with ESMTP id 5EB734A7C for ; Fri, 5 Dec 2008 15:30:02 -0800 (PST) From: Alan Hodgson Organization: Simkin Network Consulting To: pgsql-performance@postgresql.org Subject: Re: Experience with HP Smart Array P400 and SATA drives? Date: Fri, 5 Dec 2008 15:30:01 -0800 User-Agent: KMail/1.9.10 References: <4934FE60.30702@sime.com> <49395B57.EE98.0025.0@wicourts.gov> In-Reply-To: <49395B57.EE98.0025.0@wicourts.gov> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200812051530.01258@hal.medialogik.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200812/46 X-Sequence-Number: 32082 > >>> Mario Weilguni wrote: > > strange values. An individual drive is capable of delivering 91 > > MB/sec > > > sequential read performance, and we get values ~102MB/sec out of a > > 8-drive RAID5, seems to be ridiculous slow. What command are you using to test the reads? Some recommendations to try: 1) /sbin/blockdev --setra 2048 device (where device is the partition or LVM volume) 2) Use XFS, and make sure your stripe settings match the RAID. Having said that, 102MB/sec sounds really low for any modern controller with 8 drives, regardless of tuning or filesystem choice. -- Corporations will ingest natural resources and defecate garbage until all resources are depleted, debt can no longer be repaid and our money becomes worthless - Jay Hanson