Re-enabling vSAN on a cluster when "Turn off vSAN" was used to shutdown the cluster where vCenter resides on the vSAN Datastore

Products

• VMware vSAN

Issue/Introduction

 A vSAN cluster remains disabled and virtual machines (VMs) appear inaccessible after powering on ESXi hosts. This occurs when the "Turn Off vSAN" option is used during a planned maintenance window instead of the "Shutdown Cluster" wizard, or if the wizard fails with an error such as 

General vSAN Error ('NoneType' object has no attribute '_moid')

Symptoms

• esxcli vsan cluster get returns vSAN Clustering is not enabled on this host.


  [root@esxi:~] esxcli vsan cluster get
  vSAN Clustering is not enabled on this host

• Host UI for all hosts in the cluster displays the path to the VM's vmx file and not the VM's display name.
  
  
• vCenter Server Appliance (VCSA) appears as "invalid" or inaccessible in the Host Client.
  
  
• All vSAN objects show as "inaccessible".

Environment

VMware vSAN (All Versions)

Cause

Using "Turn Off vSAN" unconfigures vSAN across the cluster members. If the VCSA resides on the vSAN datastore, it cannot initialize the cluster upon power-on because the vSAN networking and membership metadata were removed.

As per KB "Turn Off vSAN" is to disable vSAN Services on the cluster not to shut down the vSAN cluster. and should NOT be used to shutdown a vSAN cluster for planned maintenance. To shut down a vSAN cluster for planned maintenance use "Shutdown Cluster" NOT "Turn Off vSAN"  

Resolution

Warning: Do not make any changes to the disks or disk groups (OSA) / storage pools (ESA), otherwise the data on the disks will be lost.

Here are the steps to re-enable vSAN on the cluster:

1. Identify the Sub-Cluster UUID: Locate the Sub-Cluster UUID of the cluster before vSAN was disabled by running the following command:

   grep nodeCount -m1 /var/run/log/vsansystem.log
   

   Example output:

   2025-11-29T15:33:40.236Z -INFO vsansystem 1000344235 [esx@4413 sub="VsanSystemProvider" opId="8269faa1-4f9b"] Complete, cluster: ####, nodeCount: 6, status: (vim.vsan.host.ClusterStatus) {

2. Check for Encryption: Determine whether encryption is in use by running this command:

   grep -m1 "Load vSAN config" /var/run/log/vsansystem.log
   

   Example output:

   2025-11-29T15:17:20.988Z -INFO vsansystem 1000344238 [esx@4413 sub="Libs" opId="4424de8a"] VsanInfoImpl: Load vSAN config enabled=1 uuid=#### clusterConfig count=1 netConfig count=1 kmsConfig count=0, kekId=, vsanMode=Mode_None, instance=B736573050

3. Join the ESXi Hosts to the vSAN Cluster: Use the Sub-Cluster UUID identified in Step 1 to rejoin the hosts.

   esxcli vsan cluster join -u <Sub-Cluster UUID>
   

   • Note: If you receive the error "vSAN can not be enabled when storage pool disks exist - eui.####", the cluster was previously configured as ESA, not OSA.

   • For ESA Clusters: Include the -x switch:

     esxcli vsan cluster join -u <Sub-Cluster UUID> -x
     

   • For Stretched Clusters (Witness Host): Include the -t switch to designate the host as a witness:

     • OSA Example: "esxcli vsan cluster join -u <Sub-Cluster UUID> -t"

     • ESA Example: "esxcli vsan cluster join -u <Sub-Cluster UUID> -x -t"

4. Rebuild the Unicast Agent List: Follow the standard KB instructions for Configuring vSAN Unicast networking from the command line

5. Validate the Cluster: Confirm the cluster is fully reformed by running:

   esxcli vsan cluster get
   

6. Power on the vCenter Appliance: Log into the host UI for all hosts in the cluster. Once the VM display names appear, locate the vCenter Server Appliance (VCSA) and power it back on.

7. Verify and Reset Advanced Settings: While vCenter is coming online, check the advanced settings on all hosts to ensure they are set to the default value of 0:

   esxcfg-advcfg -g /VSAN/DOMPauseAllCCPs
   esxcfg-advcfg -g /VSAN/IgnoreClusterMemberListUpdates
   

   If either command returns a value of 1, reset them back to default by running:

   esxcfg-advcfg -d /VSAN/DOMPauseAllCCPs
   esxcfg-advcfg -d /VSAN/IgnoreClusterMemberListUpdates
   

8. Confirm Sync: Once all vCenter services are running, log into the vCenter Web Client and confirm that vCenter and the ESXi hosts are fully in sync.

Need Help? For any further questions or issues while re-enabling vSAN, open a support case with vSAN Support for assistance.

Additional Information

To Re-install ESXi on all hosts in the cluster see KB Rebuilding a vSAN cluster after reinstalling ESXi on all hosts without vCenter while preserving production data