Entering Maintenance Mode stuck at 100% on the last node on the cluster

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Entering Maintenance Mode on the last node on the cluster is stuck at 100%
• In the vpxd.log file, you see entries similar to:
  
  Exception "vim.fault.CannotUseNetwork" with reason = "MismatchedEnsMode"

Environment

VMware vSphere ESXi 6.5
VMware vSphere ESXi 6.0
VMware vSphere ESXi 6.7

Cause

This issue occurs when the ens mode between the source host and target host are different.

ESXi 7.0.x hosts report its ens mode to the vCenter Server. However, ESXi hosts with 6.7.x and older versions does not do the same even in ens mode. The vCenter Server sees the two ESXi hosts as having two different ens mode. When the ESXi host enters Maintenance Mode, all virtual machines on this host will be migrated to other hosts. If the ens mode between the source and target host are different, this causes the Maintenance Mode to not complete.

Resolution

This behavior is by design.

Workaround:
To work around this issue, enable the VpxConfig "config.vpxd.network.allowVmotionBetweenENSModes=true in the vCenter Server User Interface (UI).

1. Log in to the vCenter Server using the vSphere Web Client.
2. Navigate to vCenter Server > Configure > Advanced Settings > Edit Settings.
3. Enable the VpxConfig with the setting "config.vpxd.network.allowVmotionBetweenENSModes=true".

Caveats: This workaround could only be used with restrictions:

1. The source host for vMotion is on version 6.7.x and below.
2. The target host for vMotion is on version 7.0.x and later.
3. The source and target host for the vMotion all work in ens mode.

Note: If the workaround is applied without these restrictions, the performance of the virtual machine traffic may degrade due to ens mode being configured.