Troubleshooting Rbd Volumegroupsnapshot Not Working In Rook Ceph

Aug 2, 2025 by ADMIN 65 views

If you're encountering issues with rbd volumegroupsnapshot in your Rook Ceph setup, you're not alone. This can be a tricky problem, but with a systematic approach, we can get it sorted out. This article aims to provide a comprehensive guide to troubleshooting this specific issue, drawing from a real-world scenario and offering practical steps to resolution.

Understanding the Problem: "rbd volumegroupsnapshot not working"

When dealing with rbd volumegroupsnapshot issues, the error message often points to a failure in taking a group snapshot of volumes. This typically manifests as a GroupSnapshotContentCheckandUpdateFailed warning. The underlying cause can be varied, but one common culprit is the inability to find the required volume for the volume group snapshot. Let's dissect the error message provided in the original issue:

Warning  GroupSnapshotContentCheckandUpdateFailed  24m   csi-snapshotter rook-ceph.rbd.csi.ceph.com  Failed to check and update group snapshot content: failed to take group snapshot of the volumes [0001-0012-rook-ceph-external-0000000000000003-a6a8ac71-3c3c-4e48-8f39-b509427db66d 0001-0012-rook-ceph-external-0000000000000003-1f8a8370-46ef-4282-b768-2081df7fba21]: "rpc error: code = InvalidArgument desc = failed to find required volume \"0001-0012-rook-ceph-external-0000000000000003-a6a8ac71-3c3c-4e48-8f39-b509427db66d\" for volume group snapshot \"groupsnapshot-0f62be19-d2a3-4344-90c9-3e6a18d65d21\": failed to get credentials: provided secret is empty"

This error message indicates that the CSI snapshotter failed to find a specific volume (0001-0012-rook-ceph-external-0000000000000003-a6a8ac71-3c3c-4e48-8f39-b509427db66d) required for the volume group snapshot. Additionally, it suggests an issue with credentials, stating that the "provided secret is empty". This could point to problems with how the snapshotter is configured to access the Ceph cluster. So addressing rbd volumegroupsnapshot issues requires a meticulous examination of the configuration, secrets, and overall health of your Rook Ceph cluster.

Reproducing the Issue: A Step-by-Step Guide

To effectively troubleshoot, it's essential to reproduce the issue in a controlled environment. Here’s a breakdown of the steps used in the original bug report to trigger the rbd volumegroupsnapshot failure. These steps involve deploying a sample application (Nginx) with persistent volume claims and then attempting to create a volume group snapshot.

VolumeGroupSnapshotClass Creation: First, a VolumeGroupSnapshotClass is created. This resource defines the driver (rook-ceph.rbd.csi.ceph.com), deletion policy, and parameters necessary for creating volume group snapshots. Pay close attention to the clusterID, csi.storage.k8s.io/snapshotter-secret-name, and csi.storage.k8s.io/snapshotter-secret-namespace parameters. These parameters are crucial for the CSI driver to connect to the Ceph cluster and authenticate correctly.
```
apiVersion: groupsnapshot.storage.k8s.io/v1beta1
kind: VolumeGroupSnapshotClass
metadata:
  name: csi-rbd-group-snapclass
driver: rook-ceph.rbd.csi.ceph.com
deletionPolicy: Delete
parameters:
  clusterID: rook-ceph-external
  csi.storage.k8s.io/snapshotter-secret-name: rook-csi-rbd-provisioner
  csi.storage.k8s.io/snapshotter-secret-namespace: rook-ceph-external
```

PersistentVolumeClaims and Deployment: Next, two PersistentVolumeClaims (nginx-rbd-html1 and nginx-rbd-html2) are created, both labeled with volume-group: nginx-rbd-group. This label is critical as it's used later to identify the volumes that should be included in the volume group snapshot. An Nginx deployment is then created, using these PVCs for storage. A service and ingress are also set up to expose the Nginx application.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nginx-rbd-html1
  labels:
    app: nginx
    volume-group: nginx-rbd-group   
spec:
  storageClassName: ceph-rbd
  accessModes: [ReadWriteOnce]
  resources:
    requests:
      storage: 100Mi
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nginx-rbd-html2
  labels:
    app: nginx
    volume-group: nginx-rbd-group  
spec:
  storageClassName: ceph-rbd
  accessModes: [ReadWriteOnce]
  resources:
    requests:
      storage: 100Mi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: registry.cn-hangzhou.aliyuncs.com/hxpdocker/nginx:latest
        ports:
        - containerPort: 80
        volumeMounts:
         - mountPath: /usr/share/nginx/html/01/
           name: html-01
         - mountPath: /usr/share/nginx/html/02/
           name: html-02
      volumes:
       - name: html-01
         persistentVolumeClaim:
           claimName: nginx-rbd-html1
           readOnly: false
       - name: html-02
         persistentVolumeClaim:
           claimName: nginx-rbd-html2
           readOnly: false
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: ClusterIP
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
spec:
  ingressClassName: nginx 
  rules:
  - host: nginx.mark.demo  
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port:
              number: 80

VolumeGroupSnapshot Creation: Finally, a VolumeGroupSnapshot resource is created. This resource references the VolumeGroupSnapshotClass and uses a selector (matchLabels: volume-group: nginx-rbd-group) to specify which volumes should be included in the snapshot.

apiVersion: groupsnapshot.storage.k8s.io/v1beta1
kind: VolumeGroupSnapshot
metadata:
  name: nginx-rbd-volume-grup-snapshot
spec:
  volumeGroupSnapshotClassName: csi-rbd-group-snapclass
  source:
    selector:
      matchLabels:
        volume-group: nginx-rbd-group

By applying these manifests, you can reproduce the environment where the rbd volumegroupsnapshot issue occurs. This is the first step in effectively troubleshooting rbd volumegroupsnapshot failures.

Diagnosing the Root Cause: A Systematic Approach

Once you can reproduce the issue, the next step is to diagnose the root cause. Based on the error message and the setup, here’s a systematic approach to identify the problem:

Verify the Snapshotter Secret: The error message “failed to get credentials: provided secret is empty” strongly suggests an issue with the secret used by the CSI snapshotter. Double-check that the secret specified in the VolumeGroupSnapshotClass (csi.storage.k8s.io/snapshotter-secret-name: rook-csi-rbd-provisioner and csi.storage.k8s.io/snapshotter-secret-namespace: rook-ceph-external) exists and contains the correct credentials. You can inspect the secret using kubectl -n <namespace> describe secret <secret-name>.
```
kubectl -n rook-ceph-external describe secret rook-csi-rbd-provisioner
```
Ensure that the secret contains the necessary keys (e.g., userID, userKey) and that the values are correct. Incorrect or missing credentials will prevent the snapshotter from accessing the Ceph cluster.
Check Volume Existence: The error message also indicates that the volume could not be found. Verify that the volumes listed in the error message (0001-0012-rook-ceph-external-0000000000000003-a6a8ac71-3c3c-4e48-8f39-b509427db66d) actually exist in your Ceph cluster. You can use the Ceph CLI within the Rook toolbox to list the RBD images.

First, get a shell in the Rook Ceph toolbox pod:
```
kubectl -n rook-ceph exec -it $(kubectl -n rook-ceph get pod -l app=rook-ceph-tools -o jsonpath='{.items[0].metadata.name}') -- bash
```
Then, list the RBD images:
```
ceph rbd ls -p rbd
```
Replace rbd with the pool name if you are not using the default pool. If the volume is missing, it could indicate a provisioning issue or accidental deletion.
Inspect CSI Driver Logs: Examine the logs of the CSI driver pods for more detailed error messages. This can provide clues about why the snapshot creation is failing. You can get the logs using kubectl -n rook-ceph logs <csi-rbd-provisioner-pod-name> -c rbd-provisioner and kubectl -n rook-ceph logs <csi-rbd-plugin-pod-name> -c rbd-plugin.
```
kubectl -n rook-ceph logs -l app=csi-rbdplugin -c rbd-plugin
kubectl -n rook-ceph logs -l app=csi-rbdplugin -c csi-attacher
kubectl -n rook-ceph logs -l app=csi-rbdplugin -c csi-snapshotter
kubectl -n rook-ceph logs -l app=csi-rbd-provisioner -c rbd-provisioner
```
Look for any errors related to authentication, volume lookup, or snapshot creation. These logs often contain valuable information about the specific failure point.
Check Ceph Health: Ensure that your Ceph cluster is healthy. Use the kubectl rook-ceph ceph status command to check the overall health of the cluster. A degraded or unhealthy Ceph cluster can lead to various issues, including snapshot failures. So monitoring ceph health is critical for a good functioning of rbd volumegroupsnapshot.
```
kubectl rook-ceph ceph status
```
Address any health issues reported by Ceph before proceeding with snapshot troubleshooting.
Verify VolumeGroupSnapshotClass Parameters: Double-check the parameters in your VolumeGroupSnapshotClass. Ensure that the clusterID matches the name of your Rook Ceph cluster, and the snapshotter-secret-name and snapshotter-secret-namespace are correctly configured. Mismatched or incorrect parameters will prevent the snapshotter from functioning correctly. Ensuring that VolumeGroupSnapshotClass parameters are correctly configured can save you a lot of time debugging.

By following these diagnostic steps, you can narrow down the root cause of the rbd volumegroupsnapshot failure. The next section will cover potential solutions based on common causes.

Resolving the Issue: Practical Solutions

Based on the diagnosis, here are some practical solutions to address the rbd volumegroupsnapshot issue:

Correct the Snapshotter Secret: If the error message indicates an empty or incorrect secret, the first step is to ensure that the secret is correctly configured. Verify that the secret exists in the specified namespace and contains the necessary credentials.

If the secret is missing, you'll need to create it. The secret should contain the userID and userKey for a Ceph user with the necessary permissions to create snapshots. For example:
```
apiVersion: v1
kind: Secret
metadata:
  name: rook-csi-rbd-provisioner
  namespace: rook-ceph-external
type: Opaque
data:
  userID: <base64-encoded-user-id>
  userKey: <base64-encoded-user-key>
```
Replace <base64-encoded-user-id> and <base64-encoded-user-key> with the base64 encoded values of your Ceph user ID and key. You can obtain these values from your Ceph configuration or by creating a new Ceph user with the appropriate permissions.

If the secret exists but the credentials are incorrect, update the secret with the correct values. After updating the secret, you may need to restart the CSI driver pods for the changes to take effect.
Ensure Volume Existence and Accessibility: If the error message indicates that the volume cannot be found, verify that the volume exists in the Ceph cluster and is accessible. Use the Ceph CLI within the Rook toolbox to list the RBD images and check their status.

If the volume is missing, investigate the provisioning process. Check the logs of the CSI provisioner and the Kubernetes events for the PVC to identify any issues during volume creation. If the volume was accidentally deleted, you may need to restore it from a backup or recreate it.

If the volume exists but is not accessible, check the Ceph cluster's health and network connectivity. Ensure that the Kubernetes nodes can communicate with the Ceph monitors and OSDs.
Address Ceph Health Issues: A degraded or unhealthy Ceph cluster can cause various issues, including snapshot failures. Use the kubectl rook-ceph ceph status command to check the overall health of the cluster and address any reported issues.

Common Ceph health issues include OSD failures, monitor quorum loss, and data imbalances. Consult the Rook Ceph documentation for guidance on resolving these issues.
Review CSI Driver Configuration: Incorrectly configured CSI drivers can also lead to snapshot failures. Review the configuration of the CSI RBD provisioner and plugin to ensure that they are correctly configured to connect to your Ceph cluster.

Check the following:
- The clusterID parameter in the CSI driver deployment should match the name of your Rook Ceph cluster.
- The CSI driver should be using the correct Ceph configuration file and keyring.
- The CSI driver should have the necessary permissions to create and manage RBD images and snapshots.
Check for Conflicting Snapshots or Operations: In some cases, existing snapshots or ongoing operations can interfere with the creation of new snapshots. Check for any existing snapshots for the volume group and any ongoing Ceph operations that might be blocking the snapshot creation.

You can list existing snapshots using the Ceph CLI:
```
ceph rbd snap ls -p <pool-name> <image-name>
```
If there are conflicting snapshots, you may need to delete them or wait for any ongoing operations to complete before creating a new snapshot.

By applying these solutions based on your diagnosis, you should be able to resolve the rbd volumegroupsnapshot issue. So fixing rbd volumegroupsnapshot requires a systematic approach and a good understanding of the underlying technologies.

Preventing Future Issues: Best Practices

To minimize the chances of encountering rbd volumegroupsnapshot issues in the future, consider implementing these best practices:

Regularly Monitor Ceph Health: Proactively monitor the health of your Ceph cluster using the kubectl rook-ceph ceph status command or a monitoring solution like Prometheus and Grafana. Address any issues promptly to prevent them from escalating.
Properly Manage Secrets: Securely manage the secrets used by the CSI driver and other components. Use Kubernetes secrets to store sensitive information and rotate them regularly. Managing Kubernetes secrets is a critical aspect of security best practices.
Validate Configurations: Before deploying or updating your Rook Ceph configuration, validate it thoroughly. Use tools like kubectl apply --dry-run to check for errors and ensure that all parameters are correctly configured.
Implement Backup and Recovery Procedures: Develop and test backup and recovery procedures for your Ceph cluster. This will help you recover from data loss or corruption and minimize downtime. Good backup and recovery procedures are essential for data protection.
Stay Up-to-Date: Keep your Rook Ceph cluster and Kubernetes environment up-to-date with the latest releases. Newer versions often include bug fixes and performance improvements that can help prevent issues.

By following these best practices, you can enhance the stability and reliability of your Rook Ceph cluster and minimize the risk of encountering rbd volumegroupsnapshot issues.

Conclusion

Troubleshooting rbd volumegroupsnapshot issues in Rook Ceph can be challenging, but by following a systematic approach and understanding the underlying causes, you can effectively resolve these problems. This guide has provided a comprehensive overview of the troubleshooting process, from reproducing the issue to diagnosing the root cause and implementing practical solutions.

Remember to pay close attention to the error messages, verify your configurations, check the health of your Ceph cluster, and implement best practices for managing your Rook Ceph environment. By doing so, you can ensure the smooth operation of your storage infrastructure and prevent future issues.