Interesting one, that's doing 50% of the job, we just need to implement the missing imagebackend.py:Qcow2.flatten() method, checking it. Matt Riedemann <mriedemos@gmail.com> wrote on ven. [2019-nov.-22 11:15:46 -0600]:
On 11/22/2019 8:05 AM, Alexandre Arents wrote:
C) Change create_image()/imagebackend driver behavior, to create a flatten qcow2 file in case of unshelving. flattening disk may be a solution because there will be no more "orphan backing file". (Basicly doing like "flat" backend driver except we need to stay in qcow2 instead of RAW) PROS: -we keep orignal unshelve behavior/assumption CONS: -It means that in your infra configured in COW some instances will be in "qcow2 flat", Flat qcow2 instance works great (livemigration/resize..). Would all installation ok with that ? Ok it seems a little odd to ask COW driver to not do COW in some case. Alternatilevy we can force using flat driver if unshelving, but we need to change flat driver to support also qcow2. D) During spawn() if unshelving we convert "qcow2 disk with backing file" to a "flatten qcow2 disk", just after self._create_image(). It looks more like a workaround than a long term solution as it need to convert something created before, that do not meet the need(better to do C).
Does this already fix your problem?
https://review.opendev.org/#/q/If3c9d1de3ce0fe394405bd1e1f0fa08ce2baeda8
--
Thanks,
Matt
-- Alexandre Arents