Rook is an open-source cloud-native storage orchestrator for Kubernetes that leverages the Ceph distributed storage system. It simplifies the deployment, management, and scaling of Ceph clusters within Kubernetes environments. Rook automates the tasks of managing storage resources, ensuring high availability and resilience.
When working with Rook and Ceph, you might encounter the issue where placement groups (PGs) are stuck in the 'creating' state. This symptom is typically observed when running ceph status or ceph -s commands, which show PGs not transitioning to the active+clean state.
The error code PG_STUCK_IN_CREATING indicates that the placement groups are unable to complete their creation process. This situation often arises due to insufficient OSDs (Object Storage Daemons) or misconfiguration in the Ceph cluster setup. PGs require a certain number of OSDs to distribute data and achieve redundancy, and any shortfall can lead to this issue.
First, check the status of your OSDs to ensure they are up and running. Use the following command:
kubectl -n rook-ceph exec deploy/rook-ceph-tools -- ceph osd status
This command will provide a list of OSDs and their current state. Ensure that all expected OSDs are present and in the 'up' state.
Review the CephCluster CRD configuration to ensure it is correctly set up. You can retrieve the current configuration with:
kubectl -n rook-ceph get cephcluster -o yaml
Look for any discrepancies or misconfigurations in the resource settings, such as the number of OSDs or replication settings.
If you find that the number of OSDs is insufficient, consider scaling up the OSDs. This can be done by adding more storage nodes or increasing the OSD count in the CephCluster CRD. For more information on scaling OSDs, refer to the Rook CephCluster CRD documentation.
After making changes, monitor the cluster to ensure that the PGs transition to the active+clean state. Use the following command to check the overall health:
kubectl -n rook-ceph exec deploy/rook-ceph-tools -- ceph status
Continue to monitor the cluster until all PGs are in the desired state.
By following these steps, you should be able to resolve the PG_STUCK_IN_CREATING issue in your Rook Ceph cluster. Ensuring that your OSDs are correctly configured and sufficient in number is crucial for the smooth operation of your storage system. For further reading, visit the official Rook documentation.
(Perfect for DevOps & SREs)
(Perfect for DevOps & SREs)
