rgw: add recovery procedure for upgrade to older version of jewel

Signed-off-by: Orit Wasserman <owasserm@redhat.com>

doc/radosgw/upgrade_to_jewel.rst

@@ -0,0 +1,37 @@
+=============
+RGW upgrade procedure to older version of jewel
+=============
+
+.. versionadded:: Jewel
+
+Upgrade of :term:`Ceph Object Gateway` to older versions of jewel (up to 10.2.3) caused issues. This document describes the needed recovery procedure.
+
+Mixed version of :term:`Ceph Object Gateway` is supported only from 10.2.4
+
+Backup of old configuration
+================
+rados mkpool .rgw.root.backup
+rados cppool .rgw.root .rgw.root.backup
+
+Fix confgiuration after upgrade
+================
+Stop all :term:`Ceph Object Gateway` running in the cluster.
+
+Run the following commands:::
+
+  $ radosgw-admin zonnegroup get --rgw-zonegroup=default | sed 's/"id":.*/"id": "default",/g' | sed 's/"master_zone.*/"master_zone":"default",/g' > default-zg.json
+
+  $ raodsgw-admin zone get --zone-id=default > default-zone.json
+
+  $ radosgw-admin realm create --rgw-realm=myrealm
+
+  $ radosgw-admin zonegroup set --rgw-zonegroup=default < default-zg.json
+
+  $ radosgw-admin zone set --rgw-zone=default < default-zone.json
+
+  $ radosgw-admin zonegroup default --rgw-zonegroup=default
+
+  $ radosgw-adminzone default --rgw-zone=default
+
+Start all :term:`Ceph Object Gateway` in the cluster.
+