From mboxrd@z Thu Jan 1 00:00:00 1970 From: dean gaudet Subject: Re: XFS sunit/swidth for raid10 Date: Thu, 22 Mar 2007 01:23:06 -0700 (PDT) Message-ID: References: <4601BE85.8050005@rabbit.us> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <4601BE85.8050005@rabbit.us> Sender: linux-raid-owner@vger.kernel.org To: Peter Rabbitson Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thu, 22 Mar 2007, Peter Rabbitson wrote: > Hi, > How does one determine the XFS sunit and swidth sizes for a software raid10 > with 3 copies? mkfs.xfs uses the GET_ARRAY_INFO ioctl to get the data it needs from software raid and select an appropriate sunit/swidth... although i'm not sure i agree entirely with its choice for raid10: *sunit = md.chunk_size >> 9; *swidth = *sunit * md.raid_disks; i'd think it would depend on the layout of the raid10 (near, far, offset)... for near2 on 4 disks i'd expect swidth to be only 2*sunit... but for far2 on 4 disks i'd expect 4*sunit... but i'm not sure. it probably doesn't matter. -dean