Understanding Ceph logs
Ceph stores its logs in the /var/log/ceph/ directory after the logging is enabled.
The CLUSTER_NAME.log is the main storage cluster log file that includes global
events. By default, the log file name is ceph.log. Only the Ceph Monitor nodes
include the main storage cluster log.
Each Ceph OSD and Monitor has its own log file named CLUSTER_NAME-osd.NUMBER.log
and CLUSTER_NAME-mon.HOSTNAME.log respectively.
When you increase debugging level for Ceph subsystems, Ceph generates new log files for those subsystems as well.
For more information about logging, see Configuring logging.
For more information about error messages, see Common Ceph Monitor error messages in Ceph logs and Common Ceph OSD error messages in Ceph logs.