Rook (Ceph Operator) Ceph manager modules are not running.

What is Rook (Ceph Operator) Ceph manager modules are not running.

Understanding Rook (Ceph Operator)

Rook is an open-source cloud-native storage orchestrator for Kubernetes that leverages the Ceph storage system. It automates the deployment, configuration, and management of Ceph clusters, providing a seamless storage solution for Kubernetes applications. The Ceph Operator in Rook manages the lifecycle of Ceph clusters, ensuring high availability and scalability of storage resources.

Identifying the Symptom: MGR_MODULES_NOT_RUNNING

When using Rook with Ceph, you might encounter an issue where the Ceph manager modules are not running. This is typically indicated by the error code MGR_MODULES_NOT_RUNNING. The Ceph manager is responsible for handling various management tasks and providing a dashboard for monitoring the cluster's health and performance.

Exploring the Issue: MGR_MODULES_NOT_RUNNING

The error MGR_MODULES_NOT_RUNNING suggests that the Ceph manager modules are not active. This can occur due to misconfigurations or insufficient resources allocated to the manager pods. Without these modules running, you might experience limited functionality in managing and monitoring your Ceph cluster.

Root Causes

Incorrect configuration of manager modules in the Ceph cluster. Resource constraints such as insufficient CPU or memory allocated to the manager pods. Network issues preventing the manager modules from communicating with other components.

Steps to Resolve the MGR_MODULES_NOT_RUNNING Issue

To resolve this issue, follow these steps:

Step 1: Check Manager Pod Logs

First, inspect the logs of the Ceph manager pods to identify any errors or warnings that might indicate the cause of the issue. Use the following command to view the logs:

kubectl logs -n rook-ceph -l app=rook-ceph-mgr

Look for any error messages or indications of misconfiguration.

Step 2: Verify Module Configurations

Ensure that the manager modules are correctly configured in your Ceph cluster. Check the Ceph configuration files or use the Ceph CLI to verify the module settings:

ceph mgr module ls

Ensure that all necessary modules are enabled and properly configured.

Step 3: Ensure Sufficient Resources

Verify that the manager pods have adequate resources allocated. Check the resource requests and limits in the CephCluster custom resource definition (CRD):

kubectl describe cephcluster -n rook-ceph

Adjust the resource allocations if necessary to ensure the manager pods have enough CPU and memory.

Step 4: Check Network Connectivity

Ensure that there are no network issues preventing the manager modules from communicating with other Ceph components. Verify the network policies and firewall settings in your Kubernetes cluster.

Additional Resources

For more information on managing Ceph clusters with Rook, refer to the following resources:

Rook Documentation Ceph Manager Modules Kubernetes Logging