From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LcOXC-0000Ni-Pu for qemu-devel@nongnu.org; Wed, 25 Feb 2009 13:31:06 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LcOXB-0000Mz-9H for qemu-devel@nongnu.org; Wed, 25 Feb 2009 13:31:06 -0500 Received: from [199.232.76.173] (port=33376 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LcOXA-0000Mr-V3 for qemu-devel@nongnu.org; Wed, 25 Feb 2009 13:31:05 -0500 Received: from qw-out-1920.google.com ([74.125.92.146]:56787) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LcOXA-00065T-Kh for qemu-devel@nongnu.org; Wed, 25 Feb 2009 13:31:04 -0500 Received: by qw-out-1920.google.com with SMTP id 4so134857qwk.4 for ; Wed, 25 Feb 2009 10:31:03 -0800 (PST) Message-ID: <49A58E64.3020303@codemonkey.ws> Date: Wed, 25 Feb 2009 12:31:00 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [6388] Stop VM on ENOSPC error. References: <49A577FD.60701@codemonkey.ws> <20090225170422.GD8810@redhat.com> <20090225173429.GV24969@redhat.com> In-Reply-To: <20090225173429.GV24969@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" , qemu-devel@nongnu.org Daniel P. Berrange wrote: > On Wed, Feb 25, 2009 at 07:04:22PM +0200, Gleb Natapov wrote: > >> Or even to stop. What guest can do with other errors anyway? >> > > The idea is that if the guest at least sees the I/O error, then it won't > continue writing as if everything were OK. It may not be able to continue > normal operation, but it can at least mark the FS read-only and avoid > ongoing damage. This simply doesn't happen in practice. The FS needs to write data to the disk in order to remount it read-only. Once all writes start failing, the errors are cascading. > So you have a reasonable liklihood of shutting down the > guest, fixing the ENOSPC problem ont he host, and starting the guests > again & them recovering their journal. 'ignore' is guarenteed dataloss, > 'report' gives you a good fighting chance. 'stop'/'enospc' are best, if > the management app is able to detect that the VM is being paused & thus > report it to the user > My contention is that a user using a management app is already hosed with "report". To not be fubar, we need async notifications. If we can the default to enospc, I think it makes nothing worse but a good chunk of cases a lot better. Regards, Anthony Liguori > Daniel >