From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx2.redhat.com (mx2.redhat.com [10.255.15.25]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l4EFO7RV016852 for ; Mon, 14 May 2007 11:24:10 -0400 Received: from mail.davidb.org (mail.davidb.org [66.93.32.219]) by mx2.redhat.com (8.13.1/8.13.1) with ESMTP id l4EFO6Y8008418 for ; Mon, 14 May 2007 11:24:06 -0400 Received: from a64.davidb.org ([66.93.32.226]) by mail.davidb.org with esmtpa (Exim 4.62 #1 (Debian)) id 1HncP8-0006rl-08 for ; Mon, 14 May 2007 08:24:06 -0700 Message-ID: <46487F15.4070108@davidb.org> Date: Mon, 14 May 2007 08:24:05 -0700 From: David Brown MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM on SATA/PATA disks References: <464672A6.3000408@davidb.org> <46481E32.4060808@redhat.com> In-Reply-To: <46481E32.4060808@redhat.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Bryn M. Reeves wrote: > David Brown wrote: > > Of course, any of the re-ordering (SCSI TCQ, or SATA NCQ) requires > > filesystem and driver support of write barriers for reliability. > > Write barriers are not implement in DM, hence LVM, so there is a > > Only the dm-mpath and dm-snap targets treat barrier bios specially (they > return EOPNOTSUPP). Other dm targets pass the barriers on to the > underlying devices unchanged. A simple lvm volume, mounted with XFS gives the following kernel message: Filesystem "dm-11": Disabling barriers, not supported by the underlying device XFS mounting filesystem dm-11 so I'm fairly sure that the write barriers don't work. This is the 2.6.20 kernel. XFS is the only filesystem nice enough to warn you that the result might not be as reliable. Dave