Heartbeat

Ceph OSDs join a cluster and report to Ceph Monitors on their status.

At the lowest level, the Ceph OSD status is up or down reflecting whether or not it is running and able to service Ceph client requests. If a Ceph OSD is down and in the Ceph storage cluster, this status may indicate the failure of the Ceph OSD. If a Ceph OSD is not running for example, it crashes the Ceph OSD cannot notify the Ceph Monitor that it is down. The Ceph Monitor can ping a Ceph OSD daemon periodically to ensure that it is running. However, heartbeating also empowers Ceph OSDs to determine if a neighboring OSD is down, to update the cluster map and to report it to the Ceph Monitors. This means that Ceph Monitors can remain light weight processes.