How to Remove a Cluster and Revert Proxmox to Standalone Mode

Need to revert your Proxmox node to a standalone setup? Here’s a step-by-step guide to help you safely remove the cluster configuration and restore standalone functionality.

Steps to Remove a Cluster

Stop Cluster Services
Run the following commands to stop cluster-related services:
```
systemctl stop pve-cluster corosync
```
Force Local Mode
Enable local mode for the Proxmox configuration file system:
```
pmxcfs -l
```
Remove Cluster Configuration
Delete the Corosync configuration files:
```
rm /etc/corosync/*
```
Remove the Proxmox cluster configuration file:
```
rm /etc/pve/corosync.conf
```
Kill Cluster File System Process
Terminate the pmxcfs process:
```
killall pmxcfs
```
Restart Services
Restart the Proxmox cluster service:
```
systemctl start pve-cluster
```

After completing these steps, your Proxmox node will no longer be part of a cluster and will function as a standalone node.

Troubleshooting: Common Errors

If you encounter issues, such as the pmxcfs command failing to acquire a lock, follow these steps:

Ensure Cluster Services Are Stopped
Verify that the pve-cluster and corosync services are completely stopped:
```
systemctl stop pve-cluster corosync
```
Kill Any Remaining Cluster Processes
Check for lingering processes related to pmxcfs:
```
ps aux | grep pmxcfs
```
Kill the processes manually using their process IDs (PIDs):
```
kill -9 <PID>
```
Retry Local Mode
After ensuring the processes are stopped, try enabling local mode again:
```
pmxcfs -l
```
Optional: Reboot the Node
If the issue persists, rebooting the node can help clear residual processes:
```
reboot
```

Conclusion

By carefully following these steps, you can successfully remove a Proxmox cluster and revert the node to a standalone setup. If you run into any challenges, don’t hesitate to revisit the troubleshooting section for guidance.