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Common Issues

Be sure to checkout the Rook Ceph Common Issues page and that all prerequisites for the storage backend of your choice are met!

Where did the rook-discover-* Pods go after a recent Rook Ceph update?

A recent change in Rook Ceph has disabled the rook-discover DaemonSet by default.
This behavior is controlled by the ROOK_ENABLE_DISCOVERY_DAEMON located in the operator.yaml or for Helm users enableDiscoveryDaemon: (false|true in your values file. It is a boolean, so false or true.

When do you want to have rook-discover-* Pods / ROOK_ENABLE_DISCOVERY_DAEMON: true?

  • You are on (plain) bare metal and / or simply have "some disks" installed /attached to your server(s), that you want to use for the Rook Ceph cluster.
  • If your cloud environment / provider does not provide PVCs with volumeMode: Block. Ceph requires block devices (Ceph's filestore is not available, through Rook, since a bunch of versions as bluestore is superior in certain ways).

Crash Collector Pods are Pending / ContainerCreating

  • Check the events of the Crash Collector Pod(s) using kubectl describe pod POD_NAME.
  • If the Pod(s) is waiting for a Secret from the Ceph MONs (keyring for each crash collector), you need to wait a bit longer as the Ceph Cluster is probably still being bootsraped / started up.
  • If they are stuck for more than 15-30 minutes, check the Rook Ceph Operator logs if it is stuck in the Ceph Cluster bootstrap / start up procedure.

No rook-ceph-mon-* Pods are running

  1. First of all make sure your Kubernetes CNI is working fine! In what feels like 90% of the cases it is network related, e.g., some weird thing with the Kubernetes cluster CNI or other network environment issue.
  2. Does your environment fit all the prerequisites? Check top of page for the links to some of the prerequisites and / or consult the docs.
  3. Check the rook-ceph-operator Logs for any warnings, errors, etc.

Disk(s) / Partition(s) not used for Ceph

A Pod can't mount its PersistentVolume after an "unclean" / "undrained" Node shutdown

  1. Check the events of the Pod using kubectl describe pod POD_NAME.
  2. Check the Node's dmesg logs.
  3. Check the kubelet logs for errors related to CSI connectivity and / or make sure the node can reach every other Kubernetes cluster node (at least the Rook Ceph cluster nodes (Ceph Mons, OSDs, MGRs, etc.)).
  4. Checkout the CSI Common Issues - Rook Docs.

Ceph CSI: Provisioning, Mounting, Deletion or something doesn't work

Make sure you have checked out the CSI Common Issues - Rook Docs.

If you have some weird kernel and / or kubelet configuration, make sure Ceph CSI's config options in the Rook Ceph Operator config is correctly setup (e.g., LIB_MODULES_DIR_PATH, ROOK_CSI_KUBELET_DIR_PATH, AGENT_MOUNTS).

Can't run any Ceph Commands in the Toolbox / Ceph Commands timeout

  • Are your rook-ceph-mon-* Pods all in Running state?
  • Does a basic ceph -s work?
  • Is your rook-ceph-mgr-* Pod(s) running as well?
  • Check the rook-ceph-mon-* and rook-ceph-mgr-* logs for errors
  • Try deleteing the toolbox Pod, "maybe it is just a fluke in your Kubernetes cluster network / CNI.
  • In case all these seem to indicate a loss of quorum, e.g., the rook-ceph-mon-* talk about probing for other mons only, you might need to follow the disaster recovery guide for your Rook Ceph version here: Rook v1.8 Docs - Ceph Disaster Recovery - Restoring Mon Quorum.

A MON Pod is running on a Node which is down

  • DO NOT EDIT THE MON DEPLOYMENT! A MON Deployment can't just be moved to another node without being failovered by the operator and / or if the MON is running using a PVC for its data.
  • As long as the operator is running the operator should see the mon being down and fail it over after a configurable timeout.
    • Env var ROOK_MON_OUT_TIMEOUT, by default 600s (10 minutes)

Remove / Replace a failed disk

Checkout the official Ceph OSD Management guide from Rook here: Rook v1.8 Docs - Ceph OSD Management.

Rook Ceph Toolbox Pod not Creating / Stuck

  • Make sure that you are not using an old version of the Rook Ceph Toolbox, grab the latest manifest here (make sure to switch to the release- branch of your Rook release):
  • The Rook Ceph Toolbox can only fully startup after a Ceph Cluster has at least passed the initial setup by the Rook Ceph operator.
    • Monitor the Rook Ceph Operator logs for errors.
  • Check the events of the Toolbox Pod using kubectl describe pod POD_NAME.

Ceph OSD Tree: Wrong Device Class

  1. Check device class, second column in ceph osd tree output.
  2. If you need to change the device class, you first must remove the current one (if it has one set): ceph osd crush rm-device-class osd.ID.
  3. Now you can set the device class for the OSD: ceph osd crush set-device-class CLASS osd.ID
  4. Default device classes (at the time of writing): hdd, ssd, nvme
  5. Source: Ceph Docs Latest - CRUSH Maps - Device Classes

HEALTH_WARN: clients are using insecure global_id reclaim / HEALTH_WARN: mons are allowing insecure global_id reclaim


I can confirm this is happening in all clusters, whether a clean install or upgraded cluster, running at least versions: v14.2.20, v15.2.11 or v16.2.1.

According to the CVE also previously mentioned, there is a security issue where clients need to be upgraded to the releases mentioned. Once all the clients are updated (e.g. the rook daemons and csi driver), a new setting needs to be applied to the cluster that will disable allowing the insecure mode.

If you see both these health warnings, then either one of the rook or csi daemons has not been upgraded yet, or some other client is detected on the older version:

        client is using insecure global_id reclaim
        mon is allowing insecure global_id reclaim

If you only see this one warning, then the insecure mode should be disabled:

        mon is allowing insecure global_id reclaim

To disable the insecure mode from the toolbox after all the clients are upgraded:
Make sure all clients have been upgraded, or else those clients will be blocked after this is set:

ceph config set mon auth_allow_insecure_global_id_reclaim false

Rook could set this flag automatically after the clients have all been updated.

Check which "Object Store" is used by an OSD

$ ceph osd metadata 0 | grep osd_objectstore
"osd_objectstore": "bluestore",

To get a quick overview of the "object stores" (bluestore, (don't use it) filestore):

$ ceph osd count-metadata osd_objectstore
    "bluestore": 6

PersistentVolumeClaims / PersistentVolumes are not Resized

  • Make sure the Ceph CSI driver for the storage (block or filesystem) is running (check the logs if you are unsure as well).
  • Check if you use a StorageClass that has allowVolumeExpansion: false:
    $ kubectl get
    rook-ceph-block      Retain          Immediate           false                  3d21h
    rook-ceph-fs   Retain          Immediate           true                   3d21h
  • To fix this simply set allowVolumeExpansion: true in the StorageClass. Below is a StorageClass with this option set, it is at the top level of the object (not in .spec or similar):
    allowVolumeExpansion: true
    kind: StorageClass
      name: rook-ceph-block
      clusterID: rook-ceph rook-csi-rbd-provisioner
      imageFeatures: layering
      imageFormat: "2"
      pool: replicapool
    reclaimPolicy: Retain
    volumeBindingMode: Immediate

[...] failed to retrieve servicemonitor. "rook-ceph-mgr" is forbidden: [...]

You have the Prometheus Operator installed in your Kubernetes cluster, but have not applied the RBAC necessary for the Rook Ceph Operator to be able to create the monitoring objects.

To rectify this, you can run the following command and / or add the file to your deployment system:

kubectl apply -f

(Original file located at:

[...] failed to reconcile cluster "rook-ceph": [...] failed to create servicemonitor. the server could not find the requested resource (post

This normally means that you don't have the Prometheus Operator installed in your Kubernetes cluster. It is required for .spec.monitoring.enabled: true in the CephCluster object to work (the operator to be able to create the ServiceMonitor object to enable monitoring).

For the Rook Ceph - Prometheus Monitoring Setup Steps check the link.

Solution A: Disable Monitoring in CephCluster

Set .spec.monitoring.enabled to false in your CephCluster object / yaml (and apply it).

Solution B: Install Prometheus Operator

If you want to use Prometheus for monitoring your applications and in this case also Rook Ceph Cluster easily in Kubernetes, make sure to install the Prometheus Operator.

Checkout the Prometheus Operator - Getting Started Guide.

unable to get monitor info from DNS SRV with service name: ceph-mon / Can't run ceph and rbd commands in the Rook Ceph XYZ Pod

You are only supposed to run ceph, rbd, radosgw-admin, etc., commands in the Rook Ceph Toolbox / Tools Pod.

Regarding the Rook Ceph Toolbox Pod checkout the Rook documentation here: Rook Ceph Docs - Ceph Toolbox.

Quick Command to Rook Ceph Toolbox Pod

This requires you to have the Rook Ceph Toolbox deployed, see Rook Ceph Docs - Ceph Toolbox for more information.

kubectl -n rook-ceph exec -it $(kubectl -n rook-ceph get pod -l "app=rook-ceph-tools" -o jsonpath='{.items[0]}') -- bash

OSD id X != my id Y - OSD Crash

  1. Exec into a working Ceph OSD on that host kubectl exec -n rook-ceph -it OSD_POD_NAME -- bash (ceph-bluestore-tool command is needed), run the following commands:
    1. Run lsblk to see all disks of the host.
    2. For every disks, run:
      1. Run ceph-bluestore-tool show-label --dev=/dev/sdX (note down the OSD ID (whoami field in the JSON output) and which disk the OSD is on (example: OSD 11 /dev/sda).
  2. The rook-ceph-osd-... deployment needs to be updated with the new/ correct device path. The ROOK_BLOCK_PATH environment variable must have the correct device path (there are two occurrences, in the containers: and in initContainers: list).
  3. After a few seconds / minutes the OSD should show up as up in the ceph osd tree output (the command can be run in the rook-ceph-tools Pod). If you have scaled down the OSD Deployment, make sure to scale it up to 1 again (kubectl scale -n rook-ceph deployment --replicas=1 rook-ceph-osd...)

_read_bdev_label failed to open /var/lib/ceph/osd/ceph-1/block: (13) Permission denied


  • OSD Pod is not starting with logs about the "ceph osd block device" and "permission denied"

Solution: Do you have the ceph package(s) installed on the host and / or a user/group named ceph?

This can potentially mess with the owner/group of the ceph osd block device, as described in GitHub rook/rook Issue 7519 "OSD pod permissions broken, unable to open OSD superblock after node restart".

You can either change the user and group ID of the ceph user on the host to the one inside the ceph/ceph image that your Rook Ceph cluster is running right now (CephCluster object .spec.cephVersion.image).

$ kubectl get -n rook-ceph rook-ceph -o yaml
kind: CephCluster
  name: rook-ceph
  namespace: rook-ceph

Depending your hosts, you might not need to even have the ceph packages installed. If you are using Rook Ceph, you normally don't need any ceph related packages on the hosts.

Should this have not fixed your issue, you might be running into some other permission issue. If your hosts are using a Linux distribution that uses SELinux, you might need to follow these steps to re-configure the Rook Ceph operator: Rook Ceph Docs - OpenShift Special Configuration Guide.

Should this page not have yielded you a solution, checkout the Ceph Common Issues doc as well.