Runtime Changes
===============
-In most cases, Ceph allows you to make changes to the configuration of
-a daemon at runtime. This capability is quite useful for
-increasing/decreasing logging output, enabling/disabling debug
-settings, and even for runtime optimization.
+In most cases, Ceph permits changes to the configuration of a daemon at
+runtime. This can be used for increasing or decreasing the amount of logging
+output, for enabling or disabling debug settings, and for runtime optimization.
-Generally speaking, configuration options can be updated in the usual
-way via the ``ceph config set`` command. For example, do enable the debug log level on a specific OSD:
+Configuration options can be updated via the ``ceph config set`` command. For
+example, to enable the debug log level on a specific OSD, run a command of this form:
.. prompt:: bash $
ceph config set osd.123 debug_ms 20
-Note that if the same option is also customized in a local
-configuration file, the monitor setting will be ignored (it has a
-lower priority than the local config file).
+.. note:: If an option has been customized in a local configuration file, the
+ `central config
+ <https://ceph.io/en/news/blog/2018/new-mimic-centralized-configuration-management/>`_
+ setting will be ignored (it has a lower priority than the local
+ configuration file).
Override values
---------------
-You can also temporarily set an option using the `tell` or `daemon`
-interfaces on the Ceph CLI. These *override* values are ephemeral in
-that they only affect the running process and are discarded/lost if
-the daemon or process restarts.
+Options can be set temporarily by using the `tell` or `daemon` interfaces on
+the Ceph CLI. These *override* values are ephemeral, which means that they
+affect only the current instance of the daemon and revert to persistently
+configured values when the daemon restarts.
Override values can be set in two ways:
-#. From any host, we can send a message to a daemon over the network with:
+#. From any host, send a message to a daemon with a command of the following
+ form:
.. prompt:: bash $
ceph tell osd.123 config set debug_osd 20
- The `tell` command can also accept a wildcard for the daemon
- identifier. For example, to adjust the debug level on all OSD
- daemons:
+ The ``tell`` command can also accept a wildcard as the daemon identifier.
+ For example, to adjust the debug level on all OSD daemons, run a command of
+ this form:
.. prompt:: bash $
ceph tell osd.* config set debug_osd 20
-#. From the host the process is running on, we can connect directly to
- the process via a socket in ``/var/run/ceph`` with:
+#. On the host where the daemon is running, connect to the daemon via a socket
+ in ``/var/run/ceph`` by running a command of this form:
.. prompt:: bash $
ceph daemon osd.4 config set debug_osd 20
-Note that in the ``ceph config show`` command output these temporary
-values will be shown with a source of ``override``.
+.. note:: In the output of the ``ceph config show`` command, these temporary
+ values are shown with a source of ``override``.
Viewing runtime settings