Hey Folks, 

Is it possible to use "cache=none" and "io=native" values with a kolla-ansible deployed cloud that uses a Ceph backend? 

Looks like that it's hard coded to use writeback for caching when the Nova backend is rbd. No globals.yaml overrides. 

https://github.com/openstack/kolla-ansible/blob/8d6b5de4c19681dd6cbec45d803185133d2ee90e/ansible/roles/nova-cell/templates/nova.conf.d/libvirt.conf.j2#L10

Cheers

Michael