From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751928Ab2G1Ieo (ORCPT ); Sat, 28 Jul 2012 04:34:44 -0400 Received: from mail-hostigation.familyross.net ([69.85.93.112]:56916 "EHLO mail.familyross.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751485Ab2G1Iel (ORCPT ); Sat, 28 Jul 2012 04:34:41 -0400 Message-ID: <5013A41E.5070500@familyross.net> Date: Sat, 28 Jul 2012 01:34:38 -0700 From: Kevin Ross User-Agent: Mozilla/5.0 (X11; Linux i686; rv:10.0.5) Gecko/20120624 Icedove/10.0.5 MIME-Version: 1.0 To: Grant Coady CC: Bill Davidsen , Linux RAID , Linux Kernel mailing List Subject: Re: RAID extremely slow References: <501078B2.8070707@familyross.net> <501096C3.5060700@turmel.org> <5010A386.4080209@familyross.net> <5010CEFF.5030606@familyross.net> <5012E717.9070808@tmr.com> <50130BEE.8080402@familyross.net> <8oq618ldps0ijt76cr3k6vovkksm4b9vsb@4ax.com> In-Reply-To: <8oq618ldps0ijt76cr3k6vovkksm4b9vsb@4ax.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/27/2012 09:45 PM, Grant Coady wrote: > On Fri, 27 Jul 2012 14:45:18 -0700, you wrote: > >> On 07/27/2012 12:08 PM, Bill Davidsen wrote: >>> Have you set the io scheduler to deadline on all members of the array? >>> That's kind of "job one" on older kernels. >>> >> I have not, thanks for the tip, I'll look into that now. > Plus I disable the on-drive queuing (NCQ) during startup, right now > I don't have benchmarks to show the difference. This on a six by 1TB > drive RAID6 array I built over a year ago on Slackware64-13.37: > > # cat /etc/rc.d/rc.local > ... > # turn off NCQ on the RAID drives by adjusting queue depth to 1 > n=1 > echo "rc.local: Disable RAID drives' NCQ" > for d in a b c d e f > do > echo " set NCQ depth to $n on sd${d}" > echo $n> /sys/block/sd${d}/device/queue_depth > done > ... > > Maybe you could try that? See if it makes a difference. My drives > are Seagate. > > Grant. > Does disabling NCQ improve performance? The suggestion to use kernel 3.4.6 has been working quite well so far, hopefully that fixes the problem. I'll know for sure in a few more days... Thanks! -- Kevin