Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id A755164FEB7 for ; Tue, 9 Dec 2008 11:30:47 -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 09691-01 for ; Tue, 9 Dec 2008 11:30:42 -0400 (AST) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-qy0-f18.google.com (mail-qy0-f18.google.com [209.85.221.18]) by mail.postgresql.org (Postfix) with ESMTP id B98D86504B6 for ; Tue, 9 Dec 2008 11:30:41 -0400 (AST) Received: by qyk11 with SMTP id 11so30361qyk.19 for ; Tue, 09 Dec 2008 07:30:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=ulHLAw6kcw+n1dkysRdyR0QJwytc3HzaECQDzD27b64=; b=f30XU4ZCgASE09dIri/jpmuCDKhgtKJf6/NXZ+gGeJEqaj0vP58BpqNPc1be5hRoy0 huf50iZZ9hd2leNtind1BX70BccJw82UA0LBu65L8KL7i4Ny2qqaXD+8krAX8Pag6YTv VmsQipW7LqldBMXtlaJTQTmGvTUCUW+dlTujI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=oAXnsjfUJConfDNiS2SpJ3snVg3maHE+RIsfATixl9PxaM9cdDlC4zloFNLLy2+n9g St5ZDnvY6RKyrBqur9I2sMgwLbABB6bCL0oWQ48+LtU+RMHP9h7Q95arx3/Gcla+Yxgr qvBzb8kcSZG8OJPKHjIKc5jAa3YMHo6US/rh0= Received: by 10.114.94.12 with SMTP id r12mr162738wab.156.1228836638898; Tue, 09 Dec 2008 07:30:38 -0800 (PST) Received: by 10.114.133.4 with HTTP; Tue, 9 Dec 2008 07:30:38 -0800 (PST) Message-ID: Date: Tue, 9 Dec 2008 08:30:38 -0700 From: "Scott Marlowe" To: "Mario Weilguni" Subject: Re: Experience with HP Smart Array P400 and SATA drives? Cc: "Alan Hodgson" , pgsql-performance@postgresql.org In-Reply-To: <493E61E1.1020303@sime.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4934FE60.30702@sime.com> <49395B57.EE98.0025.0@wicourts.gov> <200812051530.01258@hal.medialogik.com> <493E61E1.1020303@sime.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: 200812/71 X-Sequence-Number: 32107 On Tue, Dec 9, 2008 at 5:17 AM, Mario Weilguni wrote: > Alan Hodgson schrieb: >>>>>> >>>>>> 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. >> >> > > First, thanks alot for this and all the other answers. > > I measured the raw device performance: > dd if=/dev/cciss/c0d0 bs=64k count=100000 of=/dev/null > > I get poor performance when all 8 drives are configured as one, large > RAID-5, and slightly poorer performance when configured as JBOD. In > production, we use XFS as FS, but I doubt this has anything to do with FS > tuning. Yeah, having just trawled the pgsql-performance archives, there are plenty of instances of people having terrible performance from HP smart array controllers before the P800. Is it possible for you to trade up to a better RAID controller? Whichever salesman sold you the P400 should take one for the team and make this right for you.