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
