Thanks Stefan! On 5/25/11 1:21 AM, "Stefan Hajnoczi" <stefa...@gmail.com> wrote:
>On Tue, May 24, 2011 at 5:14 PM, Mike Young <myo...@wildernessvoice.com> >wrote: >> I'm trying to see if I can I do a derivative snapshot as a means of >> versioning. I wish to do this vs dd or cp as it's much faster. I do not >> intend to apply a snapshot back to an original volume. >> So, let's say I have original_volume.img and I create a snapshot using >>the >> b option: "qemu-img create f qcow2 b original_volume.img >>snapshot1.img", > >I would not call the new file "snapshot1.img" since the frozen disk >image should be original_volume.img. You can write to snapshot1.img >but it is not safe to original_volume.img because snapshot1.img will >then become inconsistent (you've changed the blocks that it was based >on). > >> but now I wish to create a snapshot2 from snapshot1.img. Is there a way >>to >> do this? > >qemu-img create -f qcow2 -b snapshot1.img snapshot2.img > >Note that you should not write to snapshot1.img anymore. However, you >could say: > >qemu-img create -f qcow2 -b snapshot1.img snapshot2a.img >qemu-img create -f qcow2 -b snapshot1.img snapshot2b.img > >Don't write to snapshot1.img but you can run VMs using snapshot2a.img >and snapshot2b.img independently. > >> Also, is there a way to generate 100% snapshot of the original volume >>(an >> exact replica), so that a 40G original results in a 40G snapshot? > >cp original.qcow2 clone.qcow2 > >Stefan
