From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: RAID1 write order fidelity Date: Fri, 01 Aug 2008 11:08:30 +0100 Message-ID: <4892E09E.3030003@dgreaves.com> References: <20080731090330.285131sc3ypxzwhu@webmail.ualberta.ca> <4891ED2F.30301@dgreaves.com> <18578.22600.936623.203944@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <18578.22600.936623.203944@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: aristizb@ualberta.ca, linux-raid@vger.kernel.org List-Id: linux-raid.ids Neil Brown wrote: >> Hence messages like: >> Filesystem "md0": Disabling barriers, not supported by the underlying device > > A strange message to get as md/RAID1 *does* support barriers when all the > underlying devices do (since the mid-teens of 2.6 I think). You specifically mention raid1 - which, granted, is what the OP asked about - is md raid1 different from other raid levels wrt barriers? Also the above message comes from XFS on a raid5 on 2.6.18 - Xen :( I thought I'd seen this on raid5 on 2.6.2[456] too though (no access to check right now) David