From mboxrd@z Thu Jan 1 00:00:00 1970 From: malahal@us.ibm.com Subject: Re: BUG in dm/dm-mirror module? Date: Tue, 14 Aug 2007 08:55:34 -0700 Message-ID: <20070814155534.GA31052@us.ibm.com> References: <20070811010853.GA9952@us.ibm.com> <46BD78B7.3080200@redhat.com> <45517CCC-7B68-4B0F-92EC-04F4E81CDA0E@redhat.com> <46C08B46.8040401@cfl.rr.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Jonathan Brassow Cc: device-mapper development List-Id: dm-devel.ids Jonathan Brassow [jbrassow@redhat.com] wrote: > > On Aug 13, 2007, at 11:48 AM, Phillip Susi wrote: > > > > >This is a problem with any mirror, not just one holding a mirror log. > > It is a special problem with the mirror log. > > Mirrors will recover themselves and become consistent upon a reboot. > In the case of a mirror that holds a file system, if you lost some of > your most recent writes, journaling/fsck will take care of it. In I believe the mirror code handles errors at region level. So one region could be out of sync while the other regions are updated with the latest data if the disk failure(s) are transient. I don't think the disk with few 'out-of-sync' regions can be assumed to have consistent data. In any case, we need a better method to select the master mirror device. Does LVM have an extra sector or so to give it to the kernel module? Thanks, Malahal.