Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754920AbZFYMCS (ORCPT ); Thu, 25 Jun 2009 08:02:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753725AbZFYMBx (ORCPT ); Thu, 25 Jun 2009 08:01:53 -0400 Received: from hole.yuiop.co.uk ([89.145.97.62]:36627 "EHLO hole.yuiop.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754772AbZFYMBu (ORCPT ); Thu, 25 Jun 2009 08:01:50 -0400 X-Greylist: delayed 1520 seconds by postgrey-1.27 at vger.kernel.org; Thu, 25 Jun 2009 08:01:50 EDT Message-ID: <4A43612F.2000100@anonymous.org.uk> Date: Thu, 25 Jun 2009 12:36:15 +0100 From: John Robinson Organization: None; Disorganization: Total User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.22) Gecko/20090605 Lightning/0.9 Thunderbird/2.0.0.22 Mnenhy/0.7.6.666 MIME-Version: 1.0 To: NeilBrown CC: "Martin K. Petersen" , Mike Snitzer , Linus Torvalds , Alasdair G Kergon , jens.axboe@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-ide@vger.kernel.org, linux-fsdevel@vger.kernel.org, device-mapper development Subject: Re: [dm-devel] REQUEST for new 'topology' metrics to be moved out of the 'queue' sysfs directory. References: <19010.62951.886231.96622@notabene.brown> <125b48b7ffc99a496fbdd512f38cada5.squirrel@neil.brown.name> In-Reply-To: <125b48b7ffc99a496fbdd512f38cada5.squirrel@neil.brown.name> 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 Content-Length: 1098 Lines: 26 On 25/06/2009 12:07, NeilBrown wrote: [...] > stripe-width is only really needed on raid4/5/6 as it is aimed at > avoiding read-modify-write, so it would be the stripe size, which would > be minimum_io_size. [...] > stride-size is used for raid0 or raid4, or the "Asymmetric" raid5 layouts. > It allows ext3 to stagger which drive certain 'hot' data structures are > on. The current metrics don't allow for that at all. > I'm not saying they should, and I'm not sure how they could. But it > is sad. Even sadder, when a raid 0/4/5/6 is reshaped over more discs (and probably other scenarios outwith md), both stripe-width and stride-size change. Is there any prospect this new stacking could give us the opportunity to tell our client (LVM, filesystem, whatever) about the change, or that they'll be able to take advantage of it? Cheers, John. -- 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/