doc: expand and consolidate mds placement

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit 3a5f9dc37a72a83046a5749e42182322799e0306)

diff --git a/doc/cephadm/services/mds.rst b/doc/cephadm/services/mds.rst
index 949a0fa5d8e7a87340c5b22ecbc017993c6eeb8d..96b7c2dda78a4476bed832fcc73664c89e65e5f9 100644 (file)
--- a/doc/cephadm/services/mds.rst
+++ b/doc/cephadm/services/mds.rst
@@ -20,7 +20,18 @@ For example:
   ceph fs volume create <fs_name> --placement="<placement spec>"
 
 where ``fs_name`` is the name of the CephFS and ``placement`` is a
-:ref:`orchestrator-cli-placement-spec`.
+:ref:`orchestrator-cli-placement-spec`. For example, to place
+MDS daemons for the new ``foo`` volume on hosts labeled with ``mds``:
+
+.. prompt:: bash #
+
+  ceph fs volume create foo --placement="label:mds"
+
+You can also update the placement after-the-fact via:
+
+.. prompt:: bash #
+
+  ceph orch apply mds foo 'mds-[012]'
 
 For manually deploying MDS daemons, use this specification:
 
@@ -30,6 +41,7 @@ For manually deploying MDS daemons, use this specification:
     service_id: fs_name
     placement:
       count: 3
+      label: mds
 
 
 The specification can then be applied using:

diff --git a/doc/cephfs/fs-volumes.rst b/doc/cephfs/fs-volumes.rst
index e25ddc5c70969471a6099f8a182906e71f947bda..6df2b3893558029c8d982b3e8715741ef752b374 100644 (file)
--- a/doc/cephfs/fs-volumes.rst
+++ b/doc/cephfs/fs-volumes.rst
@@ -42,28 +42,21 @@ FS Volumes
 
 Create a volume by running the following command:
 
-    $ ceph fs volume create <vol_name> [<placement>]
+.. prompt:: bash #
+
+   ceph fs volume create <vol_name> [placement]
 
 This creates a CephFS file system and its data and metadata pools. It can also
 deploy MDS daemons for the filesystem using a ceph-mgr orchestrator module (for
 example Rook). See :doc:`/mgr/orchestrator`.
 
-``<vol_name>`` is the volume name (an arbitrary string). ``<placement>`` is an
-optional string that specifies the hosts that should have an MDS running on
-them and, optionally, the total number of MDS daemons that the cluster should
-have. For example, the following placement string means "deploy MDS on nodes
-``host1`` and ``host2`` (one MDS per host)::
-
-    "host1,host2"
-
-The following placement specification means "deploy two MDS daemons on each of
-nodes ``host1`` and ``host2`` (for a total of four MDS daemons in the
-cluster)"::
-
-    "4 host1,host2"
+``<vol_name>`` is the volume name (an arbitrary string). ``[placement]`` is an
+optional string that specifies the :ref:`orchestrator-cli-placement-spec` for
+the MDS. See also :ref:`orchestrator-cli-cephfs` for more examples on
+placement.
 
-See :ref:`orchestrator-cli-service-spec` for more on placement specification.
-Specifying placement via a YAML file is not supported.
+.. note:: Specifying placement via a YAML file is not supported through the
+          volume interface.
 
 To remove a volume, run the following command: