rbd-mirror: use active/active policy by default

Fixes: http://tracker.ceph.com/issues/38453
Signed-off-by: Jason Dillaman <dillaman@redhat.com>

doc/releases/nautilus.rst

@@ -356,6 +356,11 @@ These changes occurred between the Mimic and Nautilus releases.
   The secrets can be set using the ``rbd mirror pool peer add`` and
   ``rbd mirror pool peer set`` actions.
 
+* The 'rbd-mirror' daemon will now run in active/active mode by default, where
+  mirrored images are evenly distributed between all active 'rbd-mirror'
+  daemons. To revert to active/passive mode, override the
+  'rbd_mirror_image_policy_type' config key to 'none'.
+
 * The ``ceph mds deactivate`` is fully obsolete and references to it in the docs
   have been removed or clarified.
 

qa/suites/rbd/mirror/workloads/rbd-mirror-ha-workunit.yaml

@@ -3,6 +3,8 @@ meta:
 overrides:
   ceph:
     conf:
+      client:
+        rbd mirror image policy type: none
       # override to make these names predictable
       client.mirror.4:
         admin socket: /var/run/ceph/rbd-mirror.$cluster-$name.asok

qa/suites/rbd/mirror/workloads/rbd-mirror-workunit-policy-none.yaml

@@ -1,5 +1,10 @@
 meta:
 - desc: run the rbd_mirror.sh workunit to test the rbd-mirror daemon
+overrides:
+  ceph:
+    conf:
+      client:
+        rbd mirror image policy type: none
 tasks:
 - workunit:
     clients:

src/common/options.cc

@@ -7318,7 +7318,7 @@ static std::vector<Option> get_rbd_mirror_options() {
     .set_description("number of failed attempts to acquire lock after missing heartbeats before breaking lock"),
 
     Option("rbd_mirror_image_policy_type", Option::TYPE_STR, Option::LEVEL_ADVANCED)
-    .set_default("none")
+    .set_default("simple")
     .set_enum_allowed({"none", "simple"})
     .set_description("active/active policy type for mapping images to instances"),