From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp2.provo.novell.com ([137.65.250.81]:36271 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932283AbeALCQq (ORCPT ); Thu, 11 Jan 2018 21:16:46 -0500 Subject: Re: Growing RAID10 with active XFS filesystem References: <20180108192607.GS5602@magnolia> <20180108220139.GB16421@dastard> <5A548D31.4000002@youngman.org.uk> <20180109222523.GJ16421@dastard> <5A55AFE7.3080500@youngman.org.uk> <20180111021441.GT16421@dastard> From: Guoqing Jiang Message-ID: <93590c11-a8f1-e4cd-acfa-ef5fb10403bb@suse.com> Date: Fri, 12 Jan 2018 10:16:23 +0800 MIME-Version: 1.0 In-Reply-To: <20180111021441.GT16421@dastard> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner , Wols Lists Cc: linux-xfs@vger.kernel.org, linux-raid@vger.kernel.org Hi Dave, On 01/11/2018 10:14 AM, Dave Chinner wrote: > >> Are you telling me that xfs is aware of the internal structure of an >> md-raid array? > It's aware of the /alignment/ characteristics of block devices, and > these alignment characteristics are exported by MD. e.g. These are > exported in /sys/block//queue in > > minimum_io_size > - typically the stripe chunk size > optimal_io_size > - typically the stripe width > > We get this stuff from DM and MD devices, hardware raid (via scsi > code pages), thinp devices (i.e. to tell us the allocation > granularity so we can align/size IO to match it) and any other block > device that wants to tell us about optimal IO geometry. libblkid > provides us with this information, and it's not just mkfs.xfs that > uses it. e.g. mkfs.ext4 also uses it for the exact same purpose as > XFS.... I see xfs can detect the geometry with "sunit" and "swidth", ext4 and gfs2 can do similar things as well. I have one question about xfs on top of raid5. Is it possible that multiple write operations happen in the same stripe at the same time? Or with the existence of those parameters, xfs would aggregate them, then it ensures no conflict happens to the parity of the stripe. Thanks in advance! Regards, Guoqing