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

• "Turn OFF vSAN" was used to shutdown the vSAN cluster
• vSAN cluster powered back on after planned cluster shutdown
  
  
• vSAN services on the hosts shows as not enabled.
  [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 Appliance resides on the vSAN datastore
  
  

Environment

VMware vSAN (All Versions)

Cause

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

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

Steps to re-enable vSAN on the cluster:

1. Identify the Sub-Cluster UUID of the cluster before vSAN was disabled

   • Use the command grep nodeCount -m1 /var/run/log/vsansystem.log to locate the Sub-Cluster UUID to re-enable vSAN.
     
     Example:
     "grep nodeCount -m1 /var/run/log/vsansystem.log"
2025-11-29T15:33:40.236Z -INFO vsansystem 1000344235 [esx@4413 sub="VsanSystemProvider" opId="8269faa1-4f9b"] Complete, cluster: 3ab1725c-cc36-11f0-93b4-############, nodeCount: 6, status: (vim.vsan.host.ClusterStatus) {
     
     

   • Also use the following command "grep -m1 "Load vSAN config" /var/run/log/vsansystem.log" and this output identifies whether encryption was in use or not.
     
     Example:
     grep -m1 "Load vSAN config" /var/run/log/vsansystem.log
2025-11-29T15:17:20.988Z -INFO vsansystem 1000344238 [esx@4413 sub="Libs" opId="4424de8a"] VsanInfoImpl: Load vSAN config enabled=1 uuid=3ab1725c-cc36-11f0-93b4-############ clusterConfig count=1 netConfig count=1 kmsConfig count=0, kekId=, vsanMode=Mode_None, instance=B736573050
     
     
2. Use the below command to join the ESXi hosts to vSAN with the vSAN cluster UUID from step 1.
   esxcli vsan cluster join -u (Sub-Cluster UUID)
Note: If the below error appears, it means the cluster was previously configured as ESA and not OSA
   vSAN can not be enabled when storage pool disks exist - eui.d77ca3707e2a688a################ ...
   
   To re-enable vSAN as ESA, include the -x switch
   Example:
esxcli vsan cluster join -u (Sub-Cluster UUID) -x
   
   when re-enabling vSAN for a stretched cluster on the witness host, include the -t switch designating 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

3. Rebuild the Unicast Agent List as per KB Configuring vSAN Unicast networking from the command line:
   
   

4. Validate the cluster is fully reformed by running esxcli vsan cluster get
5. Log into the host UI for all hosts of the cluster and the VM display names should now be displayed. Find the vCenter Appliance and power it back on.
6. While vCenter is coming online check the below advanced settings on all hosts ensuring they're set to the default of 0
   
   esxcfg-advcfg -g /VSAN/DOMPauseAllCCPs
esxcfg-advcfg -g /VSAN/IgnoreClusterMemberListUpdates
   
   If the returned value is 1 set these back to default by running the below commands
   
   esxcfg-advcfg -d /VSAN/DOMPauseAllCCPs
esxcfg-advcfg -d /VSAN/IgnoreClusterMemberListUpdates

7. Once all vCenter services are running log into the vCenter Web Client and confirm vCenter and ESX are in sync with each other.

For any further questions or issues while re-enabling vSAN please open a case with vSAN Support for further 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