Code review comment for lp:~seyeongkim/charms/trusty/ceph/lp1411652

fwiw, there's a few things at play here... the data on the OSD is intentionally not touched so that it can be reused later. Charm defaults to not reformatting the disk in an effort to prevent data loss so a user can bring the OSD back into the cluster. We'd need to check if this is handled automagically upon adding the device. In a MAAS environment, I believe the disks are wiped clean when the node is reclaimed by MAAS (an option at least). Thus, a juju destroy-unit ceph will instead be more catastrophic to the OSD themselves.