Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756113AbXFSUwN (ORCPT ); Tue, 19 Jun 2007 16:52:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751477AbXFSUv5 (ORCPT ); Tue, 19 Jun 2007 16:51:57 -0400 Received: from dsl081-033-126.lax1.dsl.speakeasy.net ([64.81.33.126]:41991 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751335AbXFSUv4 (ORCPT ); Tue, 19 Jun 2007 16:51:56 -0400 Date: Tue, 19 Jun 2007 13:51:36 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Lennart Sorensen cc: Wakko Warner , Brendan Conoboy , Neil Brown , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: limits on raid In-Reply-To: <20070619201111.GQ10008@csclub.uwaterloo.ca> Message-ID: References: <4676BEC2.7090809@redhat.com> <20070618180327.GP10008@csclub.uwaterloo.ca> <20070618183324.GL10006@csclub.uwaterloo.ca> <4676D8DE.3050903@redhat.com> <20070618214633.GA15468@animx.eu.org> <20070619201111.GQ10008@csclub.uwaterloo.ca> 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: 1349 Lines: 29 On Tue, 19 Jun 2007, Lennart Sorensen wrote: > On Mon, Jun 18, 2007 at 02:56:10PM -0700, david@lang.hm wrote: >> yes, I'm useing promise drive shelves, I have them configured to export >> the 15 drives as 15 LUNs on a single ID. >> >> I'm going to be useing this as a huge circular buffer that will just be >> overwritten eventually 99% of the time, but once in a while I will need to >> go back into the buffer and extract and process the data. > > I would guess that if you ran 15 drives per channel on 3 different > channels, you would resync in 1/3 the time. Well unless you end up > saturating the PCI bus instead. > > hardware raid of course has an advantage there in that it doesn't have > to go across the bus to do the work (although if you put 45 drives on > one scsi channel on hardware raid, it will still be limited). I fully realize that the channel will be the bottleneck, I just didn't understand what /proc/mdstat was telling me. I thought that it was telling me that the resync was processing 5M/sec, not that it was writing 5M/sec on each of the two parity locations. 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/