backups of bhyve images

[Alfred Perlstein]

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.