Witness appliance displaying alarms "Host with vsan service enabled is not in the vCenter cluster" and "Host cannot communicate with one or more other nodes in the vSAN stretched cluster"

Products

• VMware vSAN

Issue/Introduction

Symptoms:
In a Stretched Cluster, when a Witness appliance is placed inside a cluster, you may see a warning.

The cluster where the witness is placed is not the same cluster with which it is configured.

The host can display one of these alarms...

"Host with vSAN service enabled is not in the vCenter cluster"
"Host cannot communicate with one or more of the nodes in the vSAN Stretched Cluster"

Cause

These alarms are returned because the Witness Appliance should not be inside of any kind of cluster. The witness should be part of the Datacenter. The witness should not be deployed inside the 2-node or Stretched cluster it's going to be a part of.

Resolution

These alarms can be fixed by moving the witness appliance to the root of the datacenter. 

To move the witness appliance to the root of the datacenter:

Precheck: Make sure all the VM are running with "vSAN Storage Policy" applied and it should be in policy compliant state. The VM should not show " Datastore Default" policy and must be applied the appropriate policy before making any changes:
 
1 - Disable the stretched cluster from Cluster > Configure > Fault Domains & Stretched Cluster
2 - Place the witness appliance in maintenance mode.
3 - Move the witness appliance to the root of the datacenter or different cluster.  
4 - take the witness appliance out of maintenance mode.
5 - Re-enable the stretched cluster from Cluster > Configure > Fault Domains & Stretched Cluster

Check that the warnings are not being displayed anymore.