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.


Pete Wright
twitter => @nomadlogicLA

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