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...

> it's been a while since i've done this - but IIRC on NetApp WAFL systems
> (which are similar to zfs in terms of being a COW filesystem) you need
> to ensure the guest filesystem is in a consistent state before issuing a
> snapshot from it's parent.
> my data may be out of date since it's been several years since i've done
> this though...

With either UFS and ZFS, create a snapshot, and then do the copy of the
image from the snapshot... This will get you a consistant copy of the
image as if you had "powered off" the vm at that moment..  You'll still
have to fsck a UFS file system, but that is to be expected...

  John-Mark Gurney                              Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."
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