Data location

Know where cephadm daemon data and logs are located.

• /var/log/ceph/CLUSTER_FSID contains all the storage cluster logs. Note that by default cephadm logs through stderr and the container runtime, so these logs are usually not present.

• /var/lib/ceph/CLUSTER_FSID contains all the cluster daemon data, besides logs.

• /var/lib/ceph/CLUSTER_FSID/DAEMON_NAME contains all the data for a specific daemon.

• /var/lib/ceph/CLUSTER_FSID/crash contains the crash reports for the storage cluster.

• /var/lib/ceph/CLUSTER_FSID/removed contains old daemon data directories for the stateful daemons, for example monitor or Prometheus, that have been removed by cephadm.

Disk usage

A few Ceph daemons may store a significant amount of data in /var/lib/ceph, notably the monitors and Prometheus daemon, hence move this directory to its own disk, partition, or logical volume so that the root file system is not filled up.