init script won't stop an instance that's been removed from config
If an instance of a Ceph daemon is removed from the config file, then the Ceph init script no longer knows how to kill the running instance. This also means that restarting Ceph on that node (/etc/init.d/ceph restart) will leave that instance running. The only way to stop the daemon is to actually kill it.
I noticed this issue while trying to move a MDS. The new instance came up just fine, but the old instance couldn't be stopped.
(using version 0.23.1)