Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+.. _mgr-administrator-guide:
+
+ceph-mgr administrator's guide
+==============================
+
+Manual setup
+------------
+
+Usually, you would set up a ceph-mgr daemon using a tool such
+as ceph-ansible.  These instructions describe how to set up
+a ceph-mgr daemon manually.
+
+First, create an authentication key for your daemon::
+
+    ceph auth get-or-create mgr.$name mon 'allow profile mgr' osd 'allow *' mds 'allow *'
+
+Place that key as file named ``keyring`` into ``mgr data`` path, which for a cluster "ceph"
+and mgr $name "foo" would be ``/var/lib/ceph/mgr/ceph-foo`` respective ``/var/lib/ceph/mgr/ceph-foo/keyring``.
+
+Start the ceph-mgr daemon::
+
+    ceph-mgr -i $name
+
+Check that the mgr has come up by looking at the output
+of ``ceph status``, which should now include a mgr status line::
+
+    mgr active: $name
+
+Client authentication
+---------------------
+
+The manager is a new daemon which requires new CephX capabilities. If you upgrade
+a cluster from an old version of Ceph, or use the default install/deploy tools,
+your admin client should get this capability automatically. If you use tooling from
+elsewhere, you may get EACCES errors when invoking certain ceph cluster commands.
+To fix that, add a "mgr allow \*" stanza to your client's cephx capabilities by
+`Modifying User Capabilities`_.
+
+High availability
+-----------------
+
+In general, you should set up a ceph-mgr on each of the hosts
+running a ceph-mon daemon to achieve the same level of availability.
+
+By default, whichever ceph-mgr instance comes up first will be made
+active by the monitors, and the others will be standbys.  There is
+no requirement for quorum among the ceph-mgr daemons.
+
+If the active daemon fails to send a beacon to the monitors for
+more than :confval:`mon_mgr_beacon_grace`, then it will be replaced
+by a standby.
+
+If you want to preempt failover, you can explicitly mark a ceph-mgr
+daemon as failed using ``ceph mgr fail <mgr name>``.
+
+Performance and Scalability
+---------------------------
+
+All the mgr modules share a cache that can be enabled with
+``ceph config set mgr mgr_ttl_cache_expire_seconds <seconds>``, where seconds
+is the time to live of the cached python objects.
+
+It is recommended to enable the cache with a 10 seconds TTL when there are 500+
+osds or 10k+ pgs as internal structures might increase in size, and cause latency
+issues when requesting large structures. As an example, an OSDMap with 1000 osds
+has a approximate size of 4MiB. With heavy load, on a 3000 osd cluster there has
+been a 1.5x improvement enabling the cache.
+
+Furthermore, you can run ``ceph daemon mgr.${MGRNAME} perf dump`` to retrieve perf
+counters of a mgr module. In ``mgr.cache_hit`` and ``mgr.cache_miss`` you'll find the
+hit/miss ratio of the mgr cache.
+
+Using modules
+-------------
+
+Use the command ``ceph mgr module ls`` to see which modules are
+available, and which are currently enabled. Use ``ceph mgr module ls --format=json-pretty``
+to view detailed metadata about disabled modules. Enable or disable modules
+using the commands ``ceph mgr module enable <module>`` and
+``ceph mgr module disable <module>`` respectively.
+
+If a module is *enabled* then the active ceph-mgr daemon will load
+and execute it.  In the case of modules that provide a service,
+such as an HTTP server, the module may publish its address when it
+is loaded.  To see the addresses of such modules, use the command
+``ceph mgr services``.
+
+Some modules may also implement a special standby mode which runs on
+standby ceph-mgr daemons as well as the active daemon.  This enables
+modules that provide services to redirect their clients to the active
+daemon, if the client tries to connect to a standby.
+
+Consult the documentation pages for individual manager modules for more
+information about what functionality each module provides.
+
+Here is an example of enabling the :term:`Dashboard` module:
+
+.. code-block:: console
+
+	$ ceph mgr module ls
+	{
+		"enabled_modules": [
+			"restful",
+			"status"
+		],
+		"disabled_modules": [
+			"dashboard"
+		]
+	}
+
+	$ ceph mgr module enable dashboard
+	$ ceph mgr module ls
+	{
+		"enabled_modules": [
+			"restful",
+			"status",
+			"dashboard"
+		],
+		"disabled_modules": [
+		]
+	}
+
+	$ ceph mgr services
+	{
+		"dashboard": "http://myserver.com:7789/",
+		"restful": "https://myserver.com:8789/"
+	}
+
+
+The first time the cluster starts, it uses the :confval:`mgr_initial_modules`
+setting to override which modules to enable.  However, this setting
+is ignored through the rest of the lifetime of the cluster: only
+use it for bootstrapping.  For example, before starting your
+monitor daemons for the first time, you might add a section like
+this to your ``ceph.conf``:
+
+.. code-block:: ini
+
+    [mon]
+        mgr_initial_modules = dashboard balancer
+
+Module Pool
+-----------
+
+The manager creates a pool for use by its module to store state. The name of
+this pool is ``.mgr`` (with the leading ``.`` indicating a reserved pool
+name).
+
+.. note::
+
+   Prior to Quincy, the ``devicehealth`` module created a
+   ``device_health_metrics`` pool to store device SMART statistics. With
+   Quincy, this pool is automatically renamed to be the common manager module
+   pool.
+
+
+Calling module commands
+-----------------------
+
+Where a module implements command line hooks, the commands will
+be accessible as ordinary Ceph commands.  Ceph will automatically incorporate
+module commands into the standard CLI interface and route them appropriately to
+the module.::
+
+    ceph <command | help>
+
+Configuration
+-------------
+
+.. confval:: mgr_module_path
+.. confval:: mgr_initial_modules
+.. confval:: mgr_disabled_modules
+.. confval:: mgr_standby_modules
+.. confval:: mgr_data
+.. confval:: mgr_tick_period
+.. confval:: mon_mgr_beacon_grace
+
+.. _Modifying User Capabilities: ../../rados/operations/user-management/#modify-user-capabilities