ESXi Host Version Does Not Update to the Desired Image During vLCM Remediation

Products

• VMware vCenter Server

Issue/Introduction

When running ESXi remediation using vSphere Lifecycle Manager vLCM, the remediation task completes without errors but the host version does not update to the desired image.

Example: 2-node cluster with HA enabled cannot tolerate losing the second host if one is in maintenance mode, triggering the following error in the logs:

Host 'host-fqdn' reported an issue which prevents entering maintenance mode: There are insufficient memory resources on standby hosts (if any) to meet the requirements of a given operation.

Environment

VMware vCenter Server

Cause

Admission Control Policies don't allow host to enter maintenance mode.

vSphere HA’s "Specify a failover host" or "Cluster Resource Percentage" policies reserve resources for failover scenarios. In small clusters (especially 2-node setups), placing one host in maintenance mode leaves insufficient reserved resources for HA’s requirements.

 

Resolution

Option 1: Temporarily Disable HA Admission Control

In small or resource-constrained clusters (especially 2-node clusters), temporarily disabling HA Admission Control allows the host to enter Maintenance Mode.

Steps:

1. 1. Right-click the cluster in vCenter Server and select Settings
   2. Go to vSphere Availability and click Edit
   3. Select Admission Control
   4. Set Define host failover capacity by to Disabled
   5. Run the vLCM remediation
   6. Re-enable Admission Control after the upgrade completes

Option 2: Manually Place the Host into Maintenance Mode

Manually placing the host into Maintenance Mode before starting remediation.