From owner-freebsd-virtualization@FreeBSD.ORG Thu Dec 11 03:01:59 2014 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 2D1B5F66 for ; Thu, 11 Dec 2014 03:01:59 +0000 (UTC) Received: from elvis.mu.org (elvis.mu.org [IPv6:2001:470:1f05:b76::196]) by mx1.freebsd.org (Postfix) with ESMTP id 0C4E9EC3 for ; Thu, 11 Dec 2014 03:01:59 +0000 (UTC) Received: from u10-2-32-011.office.norse-data.com (unknown [50.204.88.51]) by elvis.mu.org (Postfix) with ESMTPSA id BFB07341F854 for ; Wed, 10 Dec 2014 19:01:58 -0800 (PST) Message-ID: <54890925.7060009@freebsd.org> Date: Wed, 10 Dec 2014 19:01:57 -0800 From: Alfred Perlstein Organization: FreeBSD User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: freebsd-virtualization@freebsd.org 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> <5488A1AE.4090604@nomadlogic.org> In-Reply-To: <5488A1AE.4090604@nomadlogic.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 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: Thu, 11 Dec 2014 03:01:59 -0000 On 12/10/14 11:40 AM, Pete Wright wrote: > > 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 > Hence why in the original email I wrote: *option 3 is the least safe imo as you can wind up with filesystem "angry".* in case 1 and 2 you'll have UFS snapshots that should be "OK" to restore from. in case 4 you are also doing snapshot, but you switch to ZFS.