Hi, I've asked about this in IRC already, but due to timezone foo ceph-devel might be more effective. I was wondering if there was a plan or expectation of creating cephfs subvolumes using a luminous ceph_volume_client on a nautilus cluster (or any other sensible version combination)? Currently this does not work, due to the volume client using the now removed 'ceph mds dump' command. The fix is straight forward, but depending on if that should work this could be more complex (essentially making ceph_volume_client aware of the version of the ceph cluster). I'm aware of the current refactor of the volume client as a mgr module. Will we backport this to luminous? Or is there an expectation that the volume client and the ceph cluster have to run the same version? Best, Jan -- Jan Fajerski Engineer Enterprise Storage SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)