Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753763AbYKGKbr (ORCPT ); Fri, 7 Nov 2008 05:31:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751796AbYKGKbi (ORCPT ); Fri, 7 Nov 2008 05:31:38 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:45683 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751692AbYKGKbh (ORCPT ); Fri, 7 Nov 2008 05:31:37 -0500 Subject: Re: [patch 0/4] [RFC] Another proportional weight IO controller From: Peter Zijlstra To: Dave Chinner Cc: Rik van Riel , Vivek Goyal , linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, jens.axboe@oracle.com, Hirokazu Takahashi , Ryo Tsuruta , Andrea Righi , Satoshi UCHIDA , fernando@oss.ntt.co.jp, balbir@linux.vnet.ibm.com, Andrew Morton , menage@google.com, ngupta@google.com, Jeff Moyer In-Reply-To: <20081107004131.GD2373@disturbed> References: <20081106153022.215696930@redhat.com> <1225986593.7803.4688.camel@twins> <20081106160154.GA7461@redhat.com> <1225988173.7803.4723.camel@twins> <20081106163957.GB7461@redhat.com> <1225990327.7803.4776.camel@twins> <491321ED.5010103@redhat.com> <1225991487.7803.4801.camel@twins> <20081107004131.GD2373@disturbed> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Fri, 07 Nov 2008 11:31:44 +0100 Message-Id: <1226053904.7803.5856.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1249 Lines: 31 On Fri, 2008-11-07 at 11:41 +1100, Dave Chinner wrote: > On Thu, Nov 06, 2008 at 06:11:27PM +0100, Peter Zijlstra wrote: > > On Thu, 2008-11-06 at 11:57 -0500, Rik van Riel wrote: > > > Peter Zijlstra wrote: > > > > > > > The only real issue I can see is with linear volumes, but those are > > > > stupid anyway - non of the gains but all the risks. > > > > > > Linear volumes may well be the most common ones. > > > > > > People start out with the filesystems at a certain size, > > > increasing onto a second (new) disk later, when more space > > > is required. > > > > Are they aware of how risky linear volumes are? I would discourage > > anyone from using them. > > In what way are they risky? You loose all your data when one disk dies, so your mtbf decreases with the number of disks in your linear span. And you get non of the benefits from having multiple disks, like extra speed from striping, or redundancy from raid. Therefore I say that linear volumes are the absolute worst choice. -- 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/