doc: clarify mds deactivate purpose

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/doc/cephfs/administration.rst b/doc/cephfs/administration.rst
index 1e45bb3c199aec135645d6dcd4c962cad5abb6c4..3569165fa0b540a32a892617cc5c4364ce149c15 100644 (file)
--- a/doc/cephfs/administration.rst
+++ b/doc/cephfs/administration.rst
@@ -51,6 +51,11 @@ These commands act on specific mds daemons or ranks.
 
     mds fail <gid/name/role
 
+This command deactivates an MDS causing it to flush its entire journal to
+backing RADOS objects and close all open client sessions. Deactivating an MDS
+is primarily intended for bringing down a rank after reducing the number of
+active MDS (max_mds).
+
 ::
 
     mds deactivate <role>