doc: document "ceph osd set-require-min-compat-client"

Signed-off-by: Kefu Chai <kchai@redhat.com>

diff --git a/doc/man/8/ceph.rst b/doc/man/8/ceph.rst
index a5f3de0faef9d3621a9980620decb59bfd2d04c4..ec6702a1e0f3a17ec8ea5eda188831bb2590b9f5 100644 (file)
--- a/doc/man/8/ceph.rst
+++ b/doc/man/8/ceph.rst
@@ -247,11 +247,18 @@ Usage::
 
        ceph df {detail}
 
+.. _ceph features:
 
 features
 --------
 
-Show the releases and supported features of all connected daemons and clients, along with the numbers of them in each bucket grouped by the corresponding features/releases.
+Show the releases and features of all connected daemons and clients connected
+to the cluster, along with the numbers of them in each bucket grouped by the
+corresponding features/releases. Each release of Ceph supports a different set
+of features, expressed by the features bitmask. New cluster features require
+that clients support the feature, or else they are not allowed to connect to
+these new features. As new features or capabilities are enabled after an
+upgrade, older clients are prevented from connecting.
 
 Usage::
 
@@ -1084,6 +1091,18 @@ Usage::
 
        ceph osd setmaxosd <int[0-]>
 
+Subcommand ``set-require-min-compat-client`` enforces the cluster to be backward
+compatible with the specified client version. This subcommand prevent you from
+makeing making any changes (e.g., crush tunables, or using new features) that
+would violate the current setting. Please note, This subcommand will fail if
+any connected daemon or client is not compatible with the features offered by
+the given <version>. To see the features and releases of all clients connected
+to cluster, please see `ceph features`_.
+
+Usage::
+
+    ceph osd set-require-min-compat-client <version>
+
 Subcommand ``stat`` prints summary of OSD map.
 
 Usage::

diff --git a/doc/release-notes.rst b/doc/release-notes.rst
index 3e32654e5681ea0f022b0c15a9aaa5cfa7af8619..9ab3f8b4d3a6cb0e44448d11e0be5f000452f247 100644 (file)
--- a/doc/release-notes.rst
+++ b/doc/release-notes.rst
@@ -71,11 +71,11 @@ Major Changes from Kraken
     process IO.
   * There is a `simplified OSD replacement process`_ that is more robust.
   * You can query the supported features and (apparent) releases of
-    all connected daemons and clients with ``ceph features``.
+    all connected daemons and clients with `ceph features </man/8/ceph#features>`_.
   * You can configure the oldest Ceph client version you wish to allow to
     connect to the cluster via ``ceph osd set-require-min-compat-client`` and
     Ceph will prevent you from enabling features that will break compatibility
-    with those clients.  FIXME DOCS
+    with those clients.
   * Several `sleep` settings, include ``osd_recovery_sleep``,
     ``osd_snap_trim_sleep``, and ``osd_scrub_sleep`` have been
     reimplemented to work efficiently.  (These are used in some cases