This will require some research and perhaps going one level deeper
(per-cluster and per-node granularity), but offhand:

- adding a fence device/instance that requires unfencing
  [bug 865161 comment 19]

> The docs should be updated to state that the cluster must be stopped
> while adding a fence device that requires unfencing.  (It's probably
> safest to stop the cluster while adding any fencing, but the argument
> for that is not quite so clear.)
> 
> It would also be nice if the ccs command refused to add unfencing to a
> live cluster, with an error stating the same.

Note: if there was a proper analysis in place, it would have been
      clearly a requirement for luci from the beginning