From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail01.adl2.internode.on.net ([150.101.137.133]:37607 "EHLO ipmail01.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725996AbeJEFZ1 (ORCPT ); Fri, 5 Oct 2018 01:25:27 -0400 Date: Fri, 5 Oct 2018 08:29:52 +1000 From: Dave Chinner Subject: Re: [PATCH] mkfs.xfs: don't go into multidisk mode if there is only one stripe Message-ID: <20181004222952.GV31060@dastard> References: <20181004175839.18736-1-idryomov@gmail.com> <24d229f3-1a75-a65d-5ad3-c8565cb32e76@sandeen.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <24d229f3-1a75-a65d-5ad3-c8565cb32e76@sandeen.net> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: Ilya Dryomov , linux-xfs@vger.kernel.org, Mark Nelson , Eric Sandeen On Thu, Oct 04, 2018 at 01:33:12PM -0500, Eric Sandeen wrote: > On 10/4/18 12:58 PM, Ilya Dryomov wrote: > > rbd devices report the following geometry: > > > > $ blockdev --getss --getpbsz --getiomin --getioopt /dev/rbd0 > > 512 > > 512 > > 4194304 > > 4194304 dm-thinp does this as well. THis is from the thinp device created by tests/generic/459: 512 4096 65536 65536 And I've also seen some hardware raid controllers do this, too, because they only expose the stripe width in their enquiry page rather than stripe unit and stripe width. IOWs, this behaviour isn't really specific to Ceph's rbd device, and it does occur on multi-disk devices that have something layered over the top (dm-thinp, hardware raid, etc). As such, I don't think there's a "one size fits all" solution and so someone is going to have to tweak mkfs settings to have it do the right thing for their storage subsystem.... Indeed, does Ceph really needs 4MB aligned filesystem IO? What performance benefit does that give over setting iomin=PAGE_SIZE and ioopt=0? (i.e mkfs.xfs -d sunit=0,swidth=0 or just mounting with -o noalign) Cheers, Dave. -- Dave Chinner david@fromorbit.com