vSAN Skyline Health Reports “vSAN Cluster Partition” After Re-adding Reinstalled Host

Products

• VMware vSAN

Issue/Introduction

Symptoms:

• The ESXi host operating system was reinstalled due to a hardware failure or other issue.
• The host was re-added to an existing vSAN cluster after the OS reinstallation.
• Following the rejoin, vSAN Skyline Health reports a "vSAN cluster partition" error.

• The newly added host appears as network partitioned.

Environment

• VMware vSAN 7.x
• VMware vSAN 8.x

Cause

The affected host was not properly added back to the vSAN cluster with the correct Sub-Cluster UUID, resulting in a vSAN cluster partition.

Cause validation:

• Run the command "esxcli vsan cluster get", and the output confirms a mismatch in the Sub-Cluster UUID between the affected host and the healthy cluster members.
  
  Non working host : 
  esxcli vsan cluster get
Cluster Information
   Enabled: true
   Current Local Time: YYYY-MM-DDTtt:mm:ssZ
   Local Node UUID: ########-####-####-####-############
   Local Node Type: NORMAL
   Local Node State: MASTER
   Local Node Health State: HEALTHY
     Sub-Cluster Master UUID: ########-####-####-####-############
   Sub-Cluster Backup UUID:
   Sub-Cluster UUID: ########-####-####-####-##########10
   Sub-Cluster Membership Entry Revision: 0
   Sub-Cluster Member Count: 1
  
  Working host :
  esxcli vsan cluster get
Cluster Information
   Enabled: true
   Current Local Time: YYYY-MM-DDTtt:mm:ssZ
   Local Node UUID: ########-####-####-####-############
   Local Node Type: NORMAL
   Local Node State: MASTER
   Local Node Health State: HEALTHY
   Sub-Cluster Master UUID: ########-####-####-####-############
   Sub-Cluster Backup UUID:
   Sub-Cluster UUID: ########-####-####-####-##########11
   Sub-Cluster Membership Entry Revision: 1
   Sub-Cluster Member Count: 2
   
   

Resolution

• To resolve the vSAN cluster partition issue, the affected host must be properly rejoined to the vSAN cluster with the correct Sub-Cluster UUID. Follow the steps below:

  1. Remove the host from the vSAN cluster:
     Log in to the ESXi SSH session of the affected host and run the following command to remove it from the existing (incorrect) vSAN cluster configuration:

     localcli vsan cluster leave

  2. Rejoin the host to the correct vSAN cluster:
     Identify the correct Sub-Cluster UUID from a healthy cluster member by running esxcli vsan cluster get on that host. Then, run the following command on the affected host to rejoin it to the appropriate cluster:

      

     localcli vsan cluster join -u <correct-Sub-Cluster-UUID>

  3. Verify cluster health:
     After the host has rejoined the cluster, check the vSAN Skyline Health service to ensure that the "vSAN cluster partition" health check is cleared and that the host is now properly contributing to the cluster.