doc: update stretch mode documentation for new commands

Signed-off-by: Greg Farnum <gfarnum@redhat.com>

diff --git a/doc/rados/operations/stretch-mode.rst b/doc/rados/operations/stretch-mode.rst
index 3233eae7b9258cade0eaaa811013d3dee4fdbde9..de39e80ff8581b795c9ac1fc47781027ed37a211 100644 (file)
--- a/doc/rados/operations/stretch-mode.rst
+++ b/doc/rados/operations/stretch-mode.rst
@@ -116,7 +116,8 @@ When stretch mode is enabled, the OSDs wlll only take PGs active when
 they peer across data centers (or whatever other CRUSH bucket type
 you specified), assuming both are alive. Pools will increase in size
 from the default 3 to 4, expecting 2 copies in each site. OSDs will only
-be allowed to connect to monitors in the same data center.
+be allowed to connect to monitors in the same data center. New monitors
+will not be allowed to join the cluster if they do not specify a location.
 
 If all the OSDs and monitors from a data center become inaccessible
 at once, the surviving data center will enter a degraded stretch mode. This
@@ -161,6 +162,22 @@ running with more than 2 full sites.
 
 Other commands
 ==============
+If your tiebreaker monitor fails for some reason, you can replace it. Turn on
+a new monitor and run ::
+
+  $ ceph mon set_new_tiebreaker mon.<new_mon_name>
+
+This command will protest if the new monitor is in the same location as existing
+non-tiebreaker monitors. This command WILL NOT remove the previous tiebreaker
+monitor; you should do so yourself.
+
+If you are writing your own tooling for deploying Ceph, you can use a new
+``--set-crush-location`` option when booting monitors, instead of running
+``ceph mon set_location``. This option accepts only a single "bucket=loc" pair, eg
+``ceph-mon --set-crush-location 'datacenter=a'``, which must match the
+bucket type you specified when running ``enable_stretch_mode``.
+
+
 When in stretch degraded mode, the cluster will go into "recovery" mode automatically
 when the disconnected data center comes back. If that doesn't work, or you want to
 enable recovery mode early, you can invoke ::