Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id 420B59FA38F for ; Mon, 4 Dec 2006 12:25:26 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-new, port 10024) with ESMTP id 89526-08 for ; Mon, 4 Dec 2006 12:25:13 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from exchange.g2switchworks.com (mail.g2switchworks.com [63.87.162.25]) by postgresql.org (Postfix) with ESMTP id CD27D9FA2CC for ; Mon, 4 Dec 2006 12:25:13 -0400 (AST) Received: from 10.10.1.37 ([10.10.1.37]) by exchange.g2switchworks.com ([10.10.1.2]) with Microsoft Exchange Server HTTP-DAV ; Mon, 4 Dec 2006 16:25:06 +0000 Received: from state.g2switchworks.com by mail.g2switchworks.com; 04 Dec 2006 10:25:14 -0600 Subject: Re: Bad iostat numbers From: Scott Marlowe To: Alex Turner Cc: Greg Smith , pgsql-performance@postgresql.org In-Reply-To: <33c6269f0612032317t9f0bc77n3ff791a5cd88fc80@mail.gmail.com> References: <33c6269f0612032317t9f0bc77n3ff791a5cd88fc80@mail.gmail.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1165249513.14565.329.camel@state.g2switchworks.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) Date: Mon, 04 Dec 2006 10:25:14 -0600 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200612/45 X-Sequence-Number: 22101 On Mon, 2006-12-04 at 01:17, Alex Turner wrote: > People recommend LSI MegaRAID controllers on here regularly, but I > have found that they do not work that well. I have bonnie++ numbers > that show the controller is not performing anywhere near the disk's > saturation level in a simple RAID 1 on RedHat Linux EL4 on two > seperate machines provided by two different hosting companies. In one > case I asked them to replace the card, and the numbers got a bit > better, but still not optimal. > > LSI MegaRAID has proved to be a bit of a disapointment. I have seen > better numbers from the HP SmartArray 6i, and from 3ware cards with > 7200RPM SATA drives. > > for the output: http://www.infoconinc.com/test/bonnie++.html (the > first line is a six drive RAID 10 on a 3ware 9500S, the next three are > all RAID 1s on LSI MegaRAID controllers, verified by lspci). Wait, you're comparing a MegaRAID running a RAID 1 against another controller running a 6 disk RAID10? That's hardly fair. My experience with the LSI was that with the 1.18 series drivers, they were slow but stable. With the version 2.x drivers, I found that the performance was very good with RAID-5 and fair with RAID-1 and that layered RAID was not any better than unlayered (i.e. layering RAID0 over RAID1 resulted in basic RAID-1 performance). OTOH, with the choice at my last place of employment being LSI or Adaptec, LSI was a much better choice. :) I'd ask which LSI megaraid you've tested, and what driver was used. Does RHEL4 have the megaraid 2 driver?