This document is for a development version of Ceph.

Cephadm Operations

Watching cephadm log messages

Cephadm logs to the cephadm cluster log channel, meaning you can monitor progress in realtime with:

# ceph -W cephadm

By default it will show info-level events and above. To see debug-level messages too:

# ceph config set mgr mgr/cephadm/log_to_cluster_level debug
# ceph -W cephadm --watch-debug

Be careful: the debug messages are very verbose!

You can see recent events with:

# ceph log last cephadm

These events are also logged to the ceph.cephadm.log file on monitor hosts and to the monitor daemons’ stderr.

Ceph daemon logs

Logging to stdout

Traditionally, Ceph daemons have logged to /var/log/ceph. By default, cephadm daemons log to stderr and the logs are captured by the container runtime environment. For most systems, by default, these logs are sent to journald and accessible via journalctl.

For example, to view the logs for the daemon for a cluster with ID 5c5a50ae-272a-455d-99e9-32c6a013e694, the command would be something like:

journalctl -u

This works well for normal operations when logging levels are low.

To disable logging to stderr:

ceph config set global log_to_stderr false
ceph config set global mon_cluster_log_to_stderr false

Logging to files

You can also configure Ceph daemons to log to files instead of stderr, just like they have in the past. When logging to files, Ceph logs appear in /var/log/ceph/<cluster-fsid>.

To enable logging to files:

ceph config set global log_to_file true
ceph config set global mon_cluster_log_to_file true

We recommend disabling logging to stderr (see above) or else everything will be logged twice:

ceph config set global log_to_stderr false
ceph config set global mon_cluster_log_to_stderr false

By default, cephadm sets up log rotation on each host to rotate these files. You can configure the logging retention schedule by modifying /etc/logrotate.d/ceph.<cluster-fsid>.

Data location

Cephadm daemon data and logs in slightly different locations than older versions of ceph:

  • /var/log/ceph/<cluster-fsid> contains all cluster logs. Note that by default cephadm logs via stderr and the container runtime, so these logs are normally not present.

  • /var/lib/ceph/<cluster-fsid> contains all cluster daemon data (besides logs).

  • /var/lib/ceph/<cluster-fsid>/<daemon-name> contains all data for an individual daemon.

  • /var/lib/ceph/<cluster-fsid>/crash contains crash reports for the cluster.

  • /var/lib/ceph/<cluster-fsid>/removed contains old daemon data directories for stateful daemons (e.g., monitor, prometheus) that have been removed by cephadm.

Disk usage

Because a few Ceph daemons may store a significant amount of data in /var/lib/ceph (notably, the monitors and prometheus), we recommend moving this directory to its own disk, partition, or logical volume so that it does not fill up the root file system.

Health checks

The cephadm module provides additional healthchecks to supplement the default healthchecks provided by the Cluster. These additional healthchecks fall into two categories;

  • cephadm operations: Healthchecks in this category are always executed when the cephadm module is active.

  • cluster configuration: These healthchecks are optional, and focus on the configuration of the hosts in the cluster

CEPHADM Operations


Cephadm background work has been paused with ceph orch pause. Cephadm continues to perform passive monitoring activities (like checking host and daemon status), but it will not make any changes (like deploying or removing daemons).

Resume cephadm work with:

ceph orch resume


One or more hosts have running Ceph daemons but are not registered as hosts managed by cephadm. This means that those services cannot currently be managed by cephadm (e.g., restarted, upgraded, included in ceph orch ps).

You can manage the host(s) with:

ceph orch host add *<hostname>*

Note that you may need to configure SSH access to the remote host before this will work.

Alternatively, you can manually connect to the host and ensure that services on that host are removed or migrated to a host that is managed by cephadm.

You can also disable this warning entirely with:

ceph config set mgr mgr/cephadm/warn_on_stray_hosts false

See Fully qualified domain names vs bare host names for more information about host names and domain names.


One or more Ceph daemons are running but not are not managed by cephadm. This may be because they were deployed using a different tool, or because they were started manually. Those services cannot currently be managed by cephadm (e.g., restarted, upgraded, or included in ceph orch ps).

If the daemon is a stateful one (monitor or OSD), it should be adopted by cephadm; see Converting an existing cluster to cephadm. For stateless daemons, it is usually easiest to provision a new daemon with the ceph orch apply command and then stop the unmanaged daemon.

This warning can be disabled entirely with:

ceph config set mgr mgr/cephadm/warn_on_stray_daemons false


One or more hosts have failed the basic cephadm host check, which verifies that (1) the host is reachable and cephadm can be executed there, and (2) that the host satisfies basic prerequisites, like a working container runtime (podman or docker) and working time synchronization. If this test fails, cephadm will no be able to manage services on that host.

You can manually run this check with:

ceph cephadm check-host *<hostname>*

You can remove a broken host from management with:

ceph orch host rm *<hostname>*

You can disable this health warning with:

ceph config set mgr mgr/cephadm/warn_on_failed_host_check false

Cluster Configuration Checks

Cephadm periodically scans each of the hosts in the cluster, to understand the state of the OS, disks, NICs etc. These facts can then be analysed for consistency across the hosts in the cluster to identify any configuration anomalies.

The configuration checks are an optional feature, enabled by the following command

ceph config set mgr mgr/cephadm/config_checks_enabled true

The configuration checks are triggered after each host scan (1m). The cephadm log entries will show the current state and outcome of the configuration checks as follows;

Disabled state (config_checks_enabled false)

ALL cephadm checks are disabled, use 'ceph config set mgr mgr/cephadm/config_checks_enabled true' to enable

Enabled state (config_checks_enabled true)

CEPHADM 8/8 checks enabled and executed (0 bypassed, 0 disabled). No issues detected

The configuration checks themselves are managed through several cephadm sub-commands.

To determine whether the configuration checks are enabled, you can use the following command

ceph cephadm config-check status

This command will return the status of the configuration checker as either “Enabled” or “Disabled”.

Listing all the configuration checks and their current state

ceph cephadm config-check ls

  NAME             HEALTHCHECK                      STATUS   DESCRIPTION
kernel_security  CEPHADM_CHECK_KERNEL_LSM         enabled  checks SELINUX/Apparmor profiles are consistent across cluster hosts
os_subscription  CEPHADM_CHECK_SUBSCRIPTION       enabled  checks subscription states are consistent for all cluster hosts
public_network   CEPHADM_CHECK_PUBLIC_MEMBERSHIP  enabled  check that all hosts have a NIC on the Ceph public_netork
osd_mtu_size     CEPHADM_CHECK_MTU                enabled  check that OSD hosts share a common MTU setting
osd_linkspeed    CEPHADM_CHECK_LINKSPEED          enabled  check that OSD hosts share a common linkspeed
network_missing  CEPHADM_CHECK_NETWORK_MISSING    enabled  checks that the cluster/public networks defined exist on the Ceph hosts
ceph_release     CEPHADM_CHECK_CEPH_RELEASE       enabled  check for Ceph version consistency - ceph daemons should be on the same release (unless upgrade is active)
kernel_version   CEPHADM_CHECK_KERNEL_VERSION     enabled  checks that the MAJ.MIN of the kernel on Ceph hosts is consistent

The name of each configuration check, can then be used to enable or disable a specific check.

ceph cephadm config-check disable <name>

ceph cephadm config-check disable kernel_security


Each host within the cluster is expected to operate within the same Linux Security Module (LSM) state. For example, if the majority of the hosts are running with SELINUX in enforcing mode, any host not running in this mode would be flagged as an anomaly and a healtcheck (WARNING) state raised.


This check relates to the status of vendor subscription. This check is only performed for hosts using RHEL, but helps to confirm that all your hosts are covered by an active subscription so patches and updates are available.


All members of the cluster should have NICs configured on at least one of the public network subnets. Hosts that are not on the public network will rely on routing which may affect performance


The MTU of the NICs on OSDs can be a key factor in consistent performance. This check examines hosts that are running OSD services to ensure that the MTU is configured consistently within the cluster. This is determined by establishing the MTU setting that the majority of hosts are using, with any anomalies being resulting in a Ceph healthcheck.


Similar to the MTU check, linkspeed consistency is also a factor in consistent cluster performance. This check determines the linkspeed shared by the majority of “OSD hosts”, resulting in a healthcheck for any hosts that are set at a lower linkspeed rate.


The public_network and cluster_network settings support subnet definitions for IPv4 and IPv6. If these settings are not found on any host in the cluster a healthcheck is raised.


Under normal operations, the ceph cluster should be running daemons under the same ceph release (i.e. all pacific). This check looks at the active release for each daemon, and reports any anomalies as a healthcheck. This check is bypassed if an upgrade process is active within the cluster.


The OS kernel version (maj.min) is checked for consistency across the hosts. Once again, the majority of the hosts is used as the basis of identifying anomalies.

Client keyrings and configs

Cephadm can distribute copies of the ceph.conf and client keyring files to hosts. For example, it is usually a good idea to store a copy of the config and client.admin keyring on any hosts that will be used to administer the cluster via the CLI. By default, cephadm will do this for any nodes with the _admin label (which normally includes the bootstrap host).

When a client keyring is placed under management, cephadm will:

  • build a list of target hosts based on the specified placement spec (see Placement Specification)

  • store a copy of the /etc/ceph/ceph.conf file on the specified host(s)

  • store a copy of the keyring file on the specified host(s)

  • update the ceph.conf file as needed (e.g., due to a change in the cluster monitors)

  • update the keyring file if the entity’s key is changed (e.g., via ceph auth ... commands)

  • ensure the keyring file has the specified ownership and mode

  • remove the keyring file when client keyring management is disabled

  • remove the keyring file from old hosts if the keyring placement spec is updated (as needed)

To view which client keyrings are currently under management:

ceph orch client-keyring ls

To place a keyring under management:

ceph orch client-keyring set <entity> <placement> [--mode=<mode>] [--owner=<uid>.<gid>] [--path=<path>]
  • By default, the path will be /etc/ceph/client.{entity}.keyring, which is where Ceph looks by default. Be careful specifying alternate locations as existing files may be overwritten.

  • A placement of * (all hosts) is common.

  • The mode defaults to 0600 and ownership to 0:0 (user root, group root).

For example, to create and deploy a client.rbd key to hosts with the rbd-client label and group readable by uid/gid 107 (qemu),:

ceph auth get-or-create-key client.rbd mon 'profile rbd' mgr 'profile rbd' osd 'profile rbd pool=my_rbd_pool'
ceph orch client-keyring set client.rbd label:rbd-client --owner 107:107 --mode 640

The resulting keyring file is:

-rw-r-----. 1 qemu qemu 156 Apr 21 08:47 /etc/ceph/client.client.rbd.keyring

To disable management of a keyring file:

ceph orch client-keyring rm <entity>

Note that this will delete any keyring files for this entity that were previously written to cluster nodes.


It may also be useful to distribute ceph.conf files to hosts without an associated client keyring file. By default, cephadm only deploys a ceph.conf file to hosts where a client keyring is also distributed (see above). To write config files to hosts without client keyrings:

ceph config set mgr mgr/cephadm/manage_etc_ceph_ceph_conf true

By default, the configs are written to all hosts (i.e., those listed by ceph orch host ls). To specify which hosts get a ceph.conf:

ceph config set mgr mgr/cephadm/manage_etc_ceph_ceph_conf_hosts <placement spec>

For example, to distribute configs to hosts with the bare_config label,:

ceph config set mgr mgr/cephadm/manage_etc_ceph_ceph_conf_hosts label:bare_config

(See Placement Specification for more information about placement specs.)