From owner-freebsd-virtualization@FreeBSD.ORG Wed Dec 10 19:40:37 2014 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 837D6CB5 for ; Wed, 10 Dec 2014 19:40:37 +0000 (UTC) Received: from mail.nomadlogic.org (mail.nomadlogic.org [IPv6:2607:f2f8:a098::4]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 68A40943 for ; Wed, 10 Dec 2014 19:40:37 +0000 (UTC) Received: from mail.nomadlogic.org (localhost [127.0.0.1]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by mail.nomadlogic.org (Postfix) with ESMTPS id CEE01125EE1; Wed, 10 Dec 2014 11:40:30 -0800 (PST) Received: from pop.rubicorp.com (unknown [72.34.113.100]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mail.nomadlogic.org (Postfix) with ESMTPSA id C0989125EBA; Wed, 10 Dec 2014 11:40:30 -0800 (PST) Message-ID: <5488A1AE.4090604@nomadlogic.org> Date: Wed, 10 Dec 2014 11:40:30 -0800 From: Pete Wright User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: John-Mark Gurney Subject: Re: backups of bhyve images References: <20141208163358.GA52969@potato.growveg.org> <33053EB5-91C5-4036-8CC2-34103E33A0FA@mu.org> <548637D8.1060608@nomadlogic.org> <20141210192922.GU25139@funkthat.com> In-Reply-To: <20141210192922.GU25139@funkthat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: freebsd-virtualization@freebsd.org X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Dec 2014 19:40:37 -0000 On 12/10/14 11:29, John-Mark Gurney wrote: > Pete Wright wrote this message on Mon, Dec 08, 2014 at 15:44 -0800: >> >> >> On 12/08/14 15:30, Craig Rodrigues wrote: >>> (3) When you want to backup the VM, do a "zfs snapshot" take take a >>> snapshot of the ZFS zvol. >> >> will this ensure that your zvol is consistent, or rather will the >> filesystem overlaid on the zvol device be ensured it is consistent when >> the hypervisor issues a snapshot command? > > That's the beauty of FreeBSD... UFS provides this w/ soft updates, and > ZFS does this through COW... In both cases, as far as I understand it, > it is safe to snapshot the FS... > hrm not sure I think that is a reliable methodology. You'll be forced to recover you VM's filesystem at best, and potentially have corrupt data if blocks were still sitting in cache and had not returned a filehande. My guess is that this method will work with out issues %80-%90 of the time - but you still expose yourself to possible data loss or corruption. I think you and others have mentioned the proper way to do this - snapshot the guess filesystem from with-in the guest VM itself. cheers, -pete -- Pete Wright pete@nomadlogic.org twitter => @nomadlogicLA