2 node ESXi cluster fails to automatically migrate VMs when placed into maintenance mode

Products

• VMware vSphere ESXi

Issue/Introduction

Symptom:

• Maintenance mode operation sits at a certain percentage without migrating VMs despite DRS fully automated configuration on the cluster.
  
  
  
  
  
  You will see the following within Monitor > DRS > Faults
  
  

Environment

VMware vCenter Server

Cause

• This issue is caused by HA admission control being enabled on the cluster.
  
  Refer -"To use vSphere HA admission control you must have at least 3 hosts in the cluster." 
  
  
  
  

Resolution

• To resolve this issue, disable HA admission control in the cluster or add at least 1 additional host.
  
  To disable HA admission control:
  
  
  • Cluster > Configure > vSphere Availability > Edit
    
    
  • Select the "Admission Control" tab and set "Define host failover capacity by" to "Disabled":