Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758269AbXFRRbV (ORCPT ); Mon, 18 Jun 2007 13:31:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758762AbXFRRbH (ORCPT ); Mon, 18 Jun 2007 13:31:07 -0400 Received: from dsl081-033-126.lax1.dsl.speakeasy.net ([64.81.33.126]:43116 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755000AbXFRRbG (ORCPT ); Mon, 18 Jun 2007 13:31:06 -0400 Date: Mon, 18 Jun 2007 10:28:38 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Brendan Conoboy cc: Neil Brown , Wakko Warner , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: limits on raid In-Reply-To: <4676BEC2.7090809@redhat.com> Message-ID: 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=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1301 Lines: 29 On Mon, 18 Jun 2007, Brendan Conoboy wrote: > david@lang.hm wrote: >> in my case it takes 2+ days to resync the array before I can do any >> performance testing with it. for some reason it's only doing the rebuild >> at ~5M/sec (even though I've increased the min and max rebuild speeds and >> a dd to the array seems to be ~44M/sec, even during the rebuild) > > With performance like that, it sounds like you're saturating a bus somewhere > along the line. If you're using scsi, for instance, it's very easy for a > long chain of drives to overwhelm a channel. You might also want to consider > some other RAID layouts like 1+0 or 5+0 depending upon your space vs. > reliability needs. 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. David Lang - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/