doc/cephadm: Add remove host to operations

Co-authored-by: Alexandra Settle <asettle@suse.com>
Co-authored-by: Kefu Chai <tchaikov@gmail.com>
Signed-off-by: Sebastian Wagner <sebastian.wagner@suse.com>

doc/cephadm/operations.rst

@@ -305,3 +305,53 @@ the cluster, create an initial ``ceph.conf`` file. For example::
 Then, run bootstrap referencing this file::
 
   cephadm bootstrap -c /root/ceph.conf ...
+
+
+.. _cephadm-removing-hosts:
+
+Removing Hosts
+==============
+
+If the node that want you to remove is running OSDs, make sure you remove the OSDs from the node.
+
+To remove a host from a cluster, do the following:
+
+For all Ceph service types, except for ``node-exporter`` and ``crash``, remove
+the host from the placement specification file (for example, cluster.yml).
+For example, if you are removing the host named host2, remove all occurrences of
+``- host2`` from all ``placement:`` sections.
+
+Update:
+
+.. code-block:: yaml
+
+  service_type: rgw
+  placement:
+    hosts:
+    - host1
+    - host2
+
+To:
+
+.. code-block:: yaml
+
+
+  service_type: rgw
+  placement:
+    hosts:
+    - host1
+
+Remove the host from cephadm's environment:
+
+.. code-block:: bash
+
+  ceph orch host rm host2
+
+See also :ref:`orchestrator-cli-host-management`.
+
+If the host is running ``node-exporter`` and crash services, remove them by running
+the following command on the host:
+
+.. code-block:: bash
+
+  cephadm rm-daemon --fsid CLUSTER_ID --name SERVICE_NAME

doc/mgr/orchestrator.rst

@@ -58,6 +58,8 @@ Status
 Show current orchestrator mode and high-level status (whether the orchestrator
 plugin is available and operational)
 
+.. _orchestrator-cli-host-management:
+
 Host Management
 ===============
 
@@ -70,7 +72,7 @@ Add and remove hosts::
     ceph orch host add <hostname> [<addr>] [<labels>...]
     ceph orch host rm <hostname>
 
-For cephadm, see also :ref:`cephadm-fqdn`.
+For cephadm, see also :ref:`cephadm-fqdn` and :ref:`cephadm-removing-hosts`.
 
 Host Specification
 ------------------