Date: Wed, 10 Dec 2014 19:01:57 -0800 From: Alfred Perlstein <alfred@freebsd.org> To: freebsd-virtualization@freebsd.org Subject: Re: backups of bhyve images Message-ID: <54890925.7060009@freebsd.org> In-Reply-To: <5488A1AE.4090604@nomadlogic.org> References: <20141208163358.GA52969@potato.growveg.org> <33053EB5-91C5-4036-8CC2-34103E33A0FA@mu.org> <CAG=rPVcZc_xs44mXsE%2BPrBsu9CC863HerkvqDQPTxNUEO-V4gQ@mail.gmail.com> <548637D8.1060608@nomadlogic.org> <20141210192922.GU25139@funkthat.com> <5488A1AE.4090604@nomadlogic.org>
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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.
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