Hello,
I've replaced a failing OSD (osd.1) on my cluster.
GUI: Stop -> Out -> Destroy then Create OSD with the new disk (same sdX as the removed failed one).
On the GUI, OSD tab, my 3 OSDs where present and Up/In but I did not noticed that osd.3 replaced osd.1 at first.
Now, on the Ceph TAB...