Re-adding an ESX host to an EVC cluster

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Cannot re-add an ESX host to the EVC cluster
• Adding the ESX host back to the EVC cluster fails with the error:
  
  The host cannot enter an enhanced VMotion compatibility Cluster unless all of that hosts Virtual Machine are powered off

Environment

VMware ESX Server 3.5.x
VMware vCenter Server 4.0.x
VMware ESX 4.0.x
VMware VirtualCenter 2.5.x

Resolution

This issue occurs when an ESX host is removed from an Enhanced VMotion Compatibility (EVC) cluster with powered on virtual machines still running on the ESX host.

To resolve the issue:

1. Add the ESX host back to the vCenter inventory outside of the EVC cluster.
2. VMotion the virtual machines from the ESX host, which is now outside to the EVC cluster, to ESX hosts which are in the EVC cluster. This ensures that there are no running virtual machines on the ESX host. For more information on VMotion, see the product documentation.
3. When all the virtual machines are moved from the ESX host, add it back to the EVC cluster.

Note: This does not work to add virtual machines or an ESX host that was not part of the EVC cluster previously or if the virtual machines have been rebooted since being removed from the EVC cluster.