VxRail: Prechecking if the Admission Control is Off for vSAN 2-Node Cluster Upgrade Fails

Summary: VMware's recommendation is to enable Admission Control on vSAN 2-Node clusters, but during the VxRail code upgrade of a vSAN 2-Node cluster, Admission Control must be disabled.

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Symptoms

Upgrade of a vSAN 2-Node cluster fails with the error message "Prechecking if the admission control is off for vSAN 2-Node cluster Upgrade failed."
 

Pre-check admission control on vSAN 2-Node cluster error
Figure 1: Precheck admission control on vSAN 2-Node cluster error.
 

Cause

Checking the Admission Control tab in vSphere HA shows that the Admission Control is not set to Disabled (off) but is set to something else under the "Define Host failover capacity by" dropdown. (Cluster > Configure tab > Services > vSphere Availability > vSphere HA > click Edit)
 

2-node admission control enabled
Figure 2: 2-node admission control enabled

 

 

Resolution

  1. Select the Cluster > Configure > Services > vSphere Availability. Click Edit next to vSphere HA is Turned ON.  
  2. Select the Admission Control, then record the user's current Admission Control Settings for the cluster. 
  3. Set Define host failover capacity by to Disabled.
  4. Retry the upgrade. 
  5. After the upgrade finishes, reenable user's original Admission Control settings. 
2-node admission control disabled
Figure 3: 2-node admission control disabled
 

Affected Products

VxRail, VxRail Appliance Series, VxRail Software
Article Properties
Article Number: 000205935
Article Type: Solution
Last Modified: 24 Apr 2025
Version:  3
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