vCLS VMs Fail to Deploy in vSAN Cluster Due to Datastore Marked as ‘Solution-Blocked'

Products

• VMware vSAN

Issue/Introduction

Symptoms:

• The vSAN cluster was shut down for maintenance, and after being powered back on, vCLS VMs fail to deploy.

• The vCenter Server resides on the vSAN datastore, and there are no other shared datastores available in the cluster.

• The vCenter Server is running version 8.0 U3, while the ESXi hosts are on a lower version.

• Enabling or disabling retreat mode on the cluster does not resolve the issue.
  Refer to the article Disable vCLS on a Cluster via Retreat Mode for detailed steps on using retreat mode. 

Validation Steps:

• Check if the vSAN datastore is marked as ‘Solution-Blocked’:
  Navigate to: vSphere Inventory > Cluster > Configure > vSphere Cluster Services > Datastores.
  If the datastore appears as Solution-Blocked, it may prevent vCLS deployment

  

• Refer to external vCLS datastore placement behavior:
  As documented in External vCLS Datastore Placement, datastores may be marked as blocked if vSAN is still in maintenance mode. Ensure all ESXi hosts have exited maintenance mode. SSH into each ESXi host in the cluster and run the following command:

  esxcli vsan cluster get
  Cluster Information
     Enabled: true
     Current Local Time: 2025-04-06T15:10:04Z
     Local Node UUID: 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Local Node Type: NORMAL
     Local Node State: AGENT
     Local Node Health State: HEALTHY
     Sub-Cluster Master UUID: 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Sub-Cluster Backup UUID: 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Sub-Cluster UUID: 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Sub-Cluster Membership Entry Revision: 2
     Sub-Cluster Member Count: 3
     Sub-Cluster Member UUIDs: 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx, 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx, 6xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Sub-Cluster Member HostNames: 
     Sub-Cluster Membership UUID: bxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Unicast Mode Enabled: true
     Maintenance Mode State: OFF
     Config Generation: fxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx
     Mode: REGULAR
     vSAN ESA Enabled: false

   

Environment

VMware vCenter Server 8.0U3

Cause

With vSphere 8.0 Update 3, VMware introduced a redesigned vCLS architecture called Embedded vCLS, which leverages vSphere Pod technology. Unlike the earlier External vCLS, which was managed via the vSphere ESX Agent Manager (EAM), Embedded vCLS is now natively managed by the ESXi host.

This architectural change can impact compatibility with solutions or products that have built-in logic around External vCLS behavior. Since the current vCenter Server is running version 8.0 U3 (which introduces Embedded vCLS), existing solutions are automatically marked as ‘Solution-Blocked’.

As a result, the vSAN datastore is listed under the blocked list, preventing vCLS VM deployment.

Resolution

To resolve this issue permanently, it is recommended to upgrade all ESXi hosts in the cluster to vSphere 8.0 Update 3.
This upgrade will align the ESXi host version with the vCenter Server and enable the Embedded vCLS architecture.

Once the hosts are on 8.0 U3, the vCLS VMs will transition from External to Embedded, and the vSphere ESX Agent Manager (EAM) will no longer manage their deployment.