The health check is one of the most common and important commands that a Ceph system administrator will employ frequently to stay aware of any major issues. The output of the health check gives a quick 40,000 ft. view of whether the cluster is performing normally or if it is degraded. If a cluster is unhealthy, we can use the same command to get a detailed view of where the problem lies. Even though it might not always be able tell us what the exact problem is, we can use it in almost every case to narrow our scope and focus our investigation to a very specific area.
To check the health of the cluster, we will use the health subcommand of the ceph utility.
root@ceph-client0:~# ceph healthHEALTH_OK
When Ceph cluster is ...