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Chapter 15. Cephadm operations

As a storage administrator, you can carry out Cephadm operations in the Red Hat Ceph Storage cluster.

15.1. Monitor cephadm log messages
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Cephadm logs to the cephadm cluster log channel so you can monitor progress in real time.

  • To monitor progress in realtime, run the following command:

    Example

    [ceph: root@host01 /]# ceph -W cephadm
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    Example

    2022-06-10T17:51:36.335728+0000 mgr.Ceph5-1.nqikfh [INF] refreshing Ceph5-adm facts
2022-06-10T17:51:37.170982+0000 mgr.Ceph5-1.nqikfh [INF] deploying 1 monitor(s) instead of 2 so monitors may achieve consensus
2022-06-10T17:51:37.173487+0000 mgr.Ceph5-1.nqikfh [ERR] It is NOT safe to stop ['mon.Ceph5-adm']: not enough monitors would be available (Ceph5-2) after stopping mons [Ceph5-adm]
2022-06-10T17:51:37.174415+0000 mgr.Ceph5-1.nqikfh [INF] Checking pool "nfs-ganesha" exists for service nfs.foo
2022-06-10T17:51:37.176389+0000 mgr.Ceph5-1.nqikfh [ERR] Failed to apply nfs.foo spec NFSServiceSpec({'placement': PlacementSpec(count=1), 'service_type': 'nfs', 'service_id': 'foo', 'unmanaged': False, 'preview_only': False, 'pool': 'nfs-ganesha', 'namespace': 'nfs-ns'}): Cannot find pool "nfs-ganesha" for service nfs.foo
Traceback (most recent call last):
  File "/usr/share/ceph/mgr/cephadm/serve.py", line 408, in _apply_all_services
    if self._apply_service(spec):
  File "/usr/share/ceph/mgr/cephadm/serve.py", line 509, in _apply_service
    config_func(spec)
  File "/usr/share/ceph/mgr/cephadm/services/nfs.py", line 23, in config
    self.mgr._check_pool_exists(spec.pool, spec.service_name())
  File "/usr/share/ceph/mgr/cephadm/module.py", line 1840, in _check_pool_exists
    raise OrchestratorError(f'Cannot find pool "{pool}" for '
orchestrator._interface.OrchestratorError: Cannot find pool "nfs-ganesha" for service nfs.foo
2022-06-10T17:51:37.179658+0000 mgr.Ceph5-1.nqikfh [INF] Found osd claims -> {}
2022-06-10T17:51:37.180116+0000 mgr.Ceph5-1.nqikfh [INF] Found osd claims for drivegroup all-available-devices -> {}
2022-06-10T17:51:37.182138+0000 mgr.Ceph5-1.nqikfh [INF] Applying all-available-devices on host Ceph5-adm...
2022-06-10T17:51:37.182987+0000 mgr.Ceph5-1.nqikfh [INF] Applying all-available-devices on host Ceph5-1...
2022-06-10T17:51:37.183395+0000 mgr.Ceph5-1.nqikfh [INF] Applying all-available-devices on host Ceph5-2...
2022-06-10T17:51:43.373570+0000 mgr.Ceph5-1.nqikfh [INF] Reconfiguring node-exporter.Ceph5-1 (unknown last config time)...
2022-06-10T17:51:43.373840+0000 mgr.Ceph5-1.nqikfh [INF] Reconfiguring daemon node-exporter.Ceph5-1 on Ceph5-1
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  • By default, the log displays info-level events and above. To see the debug-level messages, run the following commands:

    Example

    [ceph: root@host01 /]# ceph config set mgr mgr/cephadm/log_to_cluster_level debug
[ceph: root@host01 /]# ceph -W cephadm --watch-debug
[ceph: root@host01 /]# ceph -W cephadm --verbose
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  • Return debugging level to default info:

    Example

    [ceph: root@host01 /]# ceph config set mgr mgr/cephadm/log_to_cluster_level info
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  • To see the recent events, run the following command:

    Example

    [ceph: root@host01 /]# ceph log last cephadm
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Theses events are also logged to ceph.cephadm.log file on the monitor hosts and to the monitor daemon’s stderr

15.2. Ceph daemon logs
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You can view the Ceph daemon logs through stderr or files.

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 through the journalctl command.

  • For example, to view the logs for the daemon on host01 for a storage cluster with ID 5c5a50ae-272a-455d-99e9-32c6a013e694:

    Example

    [ceph: root@host01 /]# journalctl -u ceph-5c5a50ae-272a-455d-99e9-32c6a013e694@host01
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This works well for normal Cephadm operations when logging levels are low.

  • To disable logging to stderr, set the following values:

    Example

    [ceph: root@host01 /]# ceph config set global log_to_stderr false
[ceph: root@host01 /]# ceph config set global mon_cluster_log_to_stderr false
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Logging to files

You can also configure Ceph daemons to log to files instead of stderr. When logging to files, Ceph logs are located in /var/log/ceph/CLUSTER_FSID.

  • To enable logging to files, set the follwing values:

    Example

    [ceph: root@host01 /]# ceph config set global log_to_file true
[ceph: root@host01 /]# ceph config set global mon_cluster_log_to_file true
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Note

Red Hat recommends disabling logging to stderr to avoid double logs.

Important

Currently log rotation to a non-default path is not supported.

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.

15.3. Data location
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Cephadm daemon data and logs are located in slightly different locations than the older versions of Ceph:

  • /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 an 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 Red Hat recommends moving this directory to its own disk, partition, or logical volume so that the root file system is not filled up.

15.4. Cephadm custom config files
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Cephadm supports specifying miscellaneous configuration files for daemons. You must provide both the content of the configuration file and the location within the daemon’s container where it should be mounted.

A YAML spec is applied with custom config files specified. Cephadm redeploys the daemons for which the config files are specified. Then these files are mounted within the daemon’s container at the specified location.

  • You can apply a YAML spec with custom config files:

    Example

    service_type: grafana
service_name: grafana
custom_configs:
  - mount_path: /etc/example.conf
    content: |
      setting1 = value1
      setting2 = value2
  - mount_path: /usr/share/grafana/example.cert
    content: |
-----BEGIN PRIVATE KEY-----
V2VyIGRhcyBsaWVzdCBpc3QgZG9vZi4gTG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNldGV0dXIgc2FkaXBzY2luZyBlbGl0ciwgc2VkIGRpYW0gbm9udW15IGVpcm1vZCB0ZW1wb3IgaW52aWR1bnQgdXQgbGFib3JlIGV0IGRvbG9yZSBtYWduYSBhbGlxdXlhbSBlcmF0LCBzZWQgZGlhbSB2b2x1cHR1YS4gQXQgdmVybyBlb3MgZXQgYWNjdXNhbSBldCBqdXN0byBkdW8=
-----END PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
V2VyIGRhcyBsaWVzdCBpc3QgZG9vZi4gTG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNldGV0dXIgc2FkaXBzY2luZyBlbGl0ciwgc2VkIGRpYW0gbm9udW15IGVpcm1vZCB0ZW1wb3IgaW52aWR1bnQgdXQgbGFib3JlIGV0IGRvbG9yZSBtYWduYSBhbGlxdXlhbSBlcmF0LCBzZWQgZGlhbSB2b2x1cHR1YS4gQXQgdmVybyBlb3MgZXQgYWNjdXNhbSBldCBqdXN0byBkdW8=
-----END CERTIFICATE-----
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  • You can mount the new config files within the containers for the daemons:

    Syntax

    ceph orch redeploy SERVICE_NAME
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    Example

    [ceph: root@host01 /]# ceph orch redeploy grafana
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