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diff --git a/doc/mgr/administrator.rst b/doc/mgr/administrator.rst new file mode 100644 index 000000000..62294580a --- /dev/null +++ b/doc/mgr/administrator.rst @@ -0,0 +1,179 @@ +.. _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 into ``mgr data`` path, which for a cluster "ceph" +and mgr $name "foo" would be ``/var/lib/ceph/mgr/ceph-foo``. + +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: $name + +Client authentication +--------------------- + +The manager is a new daemon which requires new CephX capabilities. If you upgrade +a cluster from an old version of Ceph, or use the default install/deploy tools, +your admin client should get this capability automatically. If you use tooling from +elsewhere, you may get EACCES errors when invoking certain ceph cluster commands. +To fix that, add a "mgr allow \*" stanza to your client's cephx capabilities by +`Modifying User Capabilities`_. + +High availability +----------------- + +In general, you should set up a ceph-mgr on each of the hosts +running a ceph-mon daemon to achieve the same level of availability. + +By default, whichever ceph-mgr instance comes up first will be made +active by the monitors, and the others will be standbys. There is +no requirement for quorum among the ceph-mgr daemons. + +If the active daemon fails to send a beacon to the monitors for +more than ``mon mgr beacon grace`` (default 30s), then it will be replaced +by a standby. + +If you want to pre-empt failover, you can explicitly mark a ceph-mgr +daemon as failed using ``ceph mgr fail <mgr name>``. + +Performance and Scalability +--------------------------- + +All the mgr modules share a cache that can be enabled with +``ceph config set mgr mgr_ttl_cache_expire_seconds <seconds>``, where seconds +is the time to live of the cached python objects. + +It is recommended to enable the cache with a 10 seconds TTL when there are 500+ +osds or 10k+ pgs as internal structures might increase in size, and cause latency +issues when requesting large structures. As an example, an OSDMap with 1000 osds +has a aproximate size of 4MiB. With heavy load, on a 3000 osd cluster there has +been a 1.5x improvement enabling the cache. + +Furthermore, you can run ``ceph daemon mgr.${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. 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: + +:: + + $ 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 ``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``: + +:: + + [mon] + mgr_initial_modules = dashboard balancer + +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 +------------- + +``mgr_module_path`` + +:Description: Path to load modules from +:Type: String +:Default: ``"<library dir>/mgr"`` + +``mgr_data`` + +:Description: Path to load daemon data (such as keyring) +:Type: String +:Default: ``"/var/lib/ceph/mgr/$cluster-$id"`` + +``mgr_tick_period`` + +:Description: How many seconds between mgr beacons to monitors, and other + periodic checks. +:Type: Integer +:Default: ``5`` + +``mon_mgr_beacon_grace`` + +:Description: How long after last beacon should a mgr be considered failed +:Type: Integer +:Default: ``30`` + +.. _Modifying User Capabilities: ../../rados/operations/user-management/#modify-user-capabilities |