Troubleshooting

Sometimes there is a need to investigate why a cephadm command failed or why a specific service no longer runs properly.

As cephadm deploys daemons as containers, troubleshooting daemons is slightly different. Here are a few tools and commands to help investigating issues.

Pausing or disabling cephadm

If something goes wrong and cephadm is doing behaving in a way you do not like, you can pause most background activity with:

ceph orch pause

This will stop any changes, but cephadm will still periodically check hosts to refresh its inventory of daemons and devices. You can disable cephadm completely with:

ceph orch set backend ''
ceph mgr module disable cephadm

This will disable all of the ceph orch ... CLI commands but the previously deployed daemon containers will still continue to exist and start as they did before.

Checking cephadm logs

You can monitor the cephadm log in real time with:

ceph -W cephadm

You can see the last few messages with:

ceph log last cephadm

If you have enabled logging to files, you can see a cephadm log file called ceph.cephadm.log on monitor hosts (see Ceph daemon logs).

Gathering log files

Use journalctl to gather the log files of all daemons:

Note

By default cephadm now stores logs in journald. This means that you will no longer find daemon logs in /var/log/ceph/.

To read the log file of one specific daemon, run:

cephadm logs --name <name-of-daemon>

Note: this only works when run on the same host where the daemon is running. To get logs of a daemon running on a different host, give the --fsid option:

cephadm logs --fsid <fsid> --name <name-of-daemon>

where the <fsid> corresponds to the cluster ID printed by ceph status.

To fetch all log files of all daemons on a given host, run:

for name in $(cephadm ls | jq -r '.[].name') ; do
  cephadm logs --fsid <fsid> --name "$name" > $name;
done

Collecting systemd status

To print the state of a systemd unit, run:

systemctl status "ceph-$(cephadm shell ceph fsid)@<service name>.service";

To fetch all state of all daemons of a given host, run:

fsid="$(cephadm shell ceph fsid)"
for name in $(cephadm ls | jq -r '.[].name') ; do
  systemctl status "ceph-$fsid@$name.service" > $name;
done

List all downloaded container images

To list all container images that are downloaded on a host:

Note

Image might also be called ImageID

podman ps -a --format json | jq '.[].Image'
"docker.io/library/centos:8"
"registry.opensuse.org/opensuse/leap:15.2"

Manually running containers

Cephadm writes small wrappers that run a containers. Refer to /var/lib/ceph/<cluster-fsid>/<service-name>/unit.run for the container execution command.