Ceph Manager Daemon

The Ceph Manager daemon (ceph-mgr) runs alongside monitor daemons, to provide additional monitoring and interfaces to external monitoring and management systems.

Since the 12.x (luminous) Ceph release, the ceph-mgr daemon is required for normal operations. The ceph-mgr daemon is an optional component in the 11.x (kraken) Ceph release.

By default, the manager daemon requires no additional configuration, beyond ensuring it is running. If there is no mgr daemon running, you will see a health warning to that effect, and some of the other information in the output of ceph status will be missing or stale until a mgr is started.

Use your normal deployment tools, such as ceph-ansible or cephadm, to set up ceph-mgr daemons on each of your mon nodes. It is not mandatory to place mgr daemons on the same nodes as mons, but it is almost always sensible.