What is a vCLS Virtual Machine and How to Troubleshoot It

vCLS VMs (vSphere Cluster Services Virtual Machines) are a new feature introduced in VMware vSphere 7.0 Update 1. vCLS VMs are a critical part of the new vSphere Cluster Services functionality, which provides an infrastructure service that ensures the availability of critical vSphere cluster services.

vCLS VMs are lightweight virtual machines that are deployed on each ESXi host in a vSphere cluster. They are responsible for running cluster-level services, such as vSphere Distributed Resource Scheduler (DRS), vSphere High Availability (HA), and vSphere vMotion. vCLS VMs are automatically created and managed by vSphere and are designed to be highly available and resilient to failures.

It is not recommended to permanently disable vCLS VMs in a vSphere cluster. vCLS VMs are critical components of the vSphere Cluster Services functionality and are required to ensure the availability of critical vSphere cluster services. Disabling or removing vCLS VMs can cause issues with the availability and performance of vSphere cluster services, which can lead to service disruptions and impact your environment.

Troubleshooting vCLS Issues

Some users are experiencing high CPU usage on vCLS VMs after upgrading to vSphere 8.0 Update 1. To troubleshoot vCLS issues, check the vSphere ESX Agent Manager (EAM) log located in /var/log/vmware/eam/eam.log.

If you’ve noticed performance or any other issue on vCLS VMs, it’s worth trying to re-enable vCLS. Most issues can be resolved by disabling vCLS and then enabling vCLS in vCenter.

How to Disable vCLS Virtual Machines

1. Login to vCenter.

https://vCenter_IP_or_hostname

2. Get the Cluster ID. Click Cluster and make a note of domain-c# from URL.

3. In vCenter click Configure, then Advanced Settings and Edit Settings.

4. In the Edit Advanced vCenter Server Settings window add the following:

Name: config.vcls.clusters.cluster-ID.enabled

Value: False

Remember to change cluster-ID to your value.

For me it would be config.vcls.clusters.domain-c16.enabled.

Cick Add and Save.

5. In the next few minutes, you will see tasks to shutdon and delete vCLS VMs.

How to Enable vCLS Virtual Machines

To enable vCLS VMs, follow the same steps as for disabling. The only difference is changing the value for an existing configuration.

1. In vCenter click Configure, then Advanced Settings and Edit Settings.

2. In Edit Advanced vCenter Server Settings filter by Name.

3. Enter the name of your configuration, for me it would be config.vcls.clusters.domain-c16.enabled.

Change the Value to True and click Save.

4. In the next few minutes, you will see tasks to deploy and power on vCLS VMs.

This is how you can re-enable vCLS Virtual Machines which may resolve potential issues.

Thank you for reading! Here are some links you may be interested in:

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