From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brendan Conoboy Subject: Re: limits on raid Date: Mon, 18 Jun 2007 12:07:59 -0600 Message-ID: <4676C9FF.7060607@redhat.com> References: <18034.479.256870.600360@notabene.brown> <18034.3676.477575.490448@notabene.brown> <20070616020320.GB2002@animx.eu.org> <18035.23867.576212.859440@notabene.brown> <4676BEC2.7090809@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: david@lang.hm Cc: Neil Brown , Wakko Warner , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org List-Id: linux-raid.ids david@lang.hm wrote: > I plan to test the different configurations. > > however, if I was saturating the bus with the reconstruct how can I fire > off a dd if=/dev/zero of=/mnt/test and get ~45M/sec whild only slowing > the reconstruct to ~4M/sec? > > I'm putting 10x as much data through the bus at that point, it would > seem to proove that it's not the bus that's saturated. I am unconvinced. If you take ~1MB/s for each active drive, add in SCSI overhead, 45M/sec seems reasonable. Have you look at a running iostat while all this is going on? Try it out- add up the kb/s from each drive and see how close you are to your maximum theoretical IO. Also, how's your CPU utilization? -- Brendan Conoboy / Red Hat, Inc. / blc@redhat.com