So, it looks like xz is not supported by OpenStack.
"So what" you say "OpenStack should use QCOW anyway."
Not with Ceph. Ceph does its own COW semantics with raw, and the qcow.
formats are not supported. (Yes that is a regular expression dot there)
And, this is a pretty big use case. IS there some way we can convert
the compression to a format supported by OpenStack, either .zip or
.tar.gz (yes, tar for some reason) or produce that as well as the xz