vSAN disk group shows unhealthy

Products

• VMware vSAN

Issue/Introduction

• In vCenter UI, Cluster > Configure > vSAN > Disk Management shows the vSAN disk group as 'Unhealthy'.

• 'esxcli vsan storage list' command from the Host CLI will show the Disk group status as 'Mounted', but the CMMDS status as 'False'.
  
  

  [root@ESXi01:~] localcli vsan storage list

  mpx.vmhba0:C0:T4:L0:
   Device: mpx.vmhba0:C0:T4:L0
   Display Name: mpx.vmhba0:C0:T1:L0
   Is SSD: true
   VSAN UUID: 529d0e00-1c24-b7f7-127e-############
   VSAN Disk Group UUID: 529d0e00-1c24-b7f7-127e-############
   VSAN Disk Group Name: mpx.vmhba0:C0:T4:L0
   Used by this host: false
   In CMMDS: false
   On-disk format version: 20
   Deduplication: false
   Compression: false
   Checksum: 117883488320670227
   Checksum OK: true
   Is Capacity Tier: false
   Encryption Metadata Checksum OK: true
   Encryption: false
   DiskKeyLoaded: false
   Is Mounted: true
   Creation Time: Sat Oct 18 06:21:02 2025

Environment

VMware vSAN 7.x
VMware vSAN 8.x

Cause

If vSAN Clustering is not enabled on the host, the disk groups which are part of that host will show as Unhealthy.

[root@ESXi01:~] localcli vsan cluster get
Errors:
vSAN Clustering is not enabled on this host

Resolution

Join the host back to the vSAN cluster via CLI.

Follow the below steps to join the host to the existing vSAN cluster: 

1. Connect to one of the remaining vSAN cluster hosts using SSH.
2. Identify the vSAN Sub Cluster ID using this command:
   
   # esxcli vsan cluster get
   
   You see output similar to:
   
   Cluster Information
Enabled: true
Current Local Time: YYYY-MM-DDTHH:MM:SS
Local Node UUID: ########-####-####-####-########826f
Local Node Type: NORMAL
Local Node State: AGENT
Local Node Health State: HEALTHY
Sub-Cluster Master UUID: ########-####-####-####-########f17d
Sub-Cluster Backup UUID: ########-####-####-####-########dd93
Sub-Cluster UUID: ########-####-####-####-########9e45
Sub-Cluster Membership Entry Revision: 2
Sub-Cluster Member Count: 3
Sub-Cluster Member UUIDs: ########-####-####-####-########f17d, ########-####-####-####-########dd93, ########-####-####-####-########826f
Sub-Cluster Member HostNames: esxi2.########, esxi3.########, esxi4.########
Sub-Cluster Membership UUID: ########-####-####-####-########f17d
Unicast Mode Enabled: true
Maintenance Mode State: OFF
Config Generation: ########-####-####-####-########d2c2 3 YYYY-MM-DDTHH:MM:SS
Mode: REGULAR
vSAN ESA Enabled: false
    
3. Run one of the commands below on the newly rebuilt ESXi host using the Sub Cluster UUID identified in step 2:
   
   
   • For vSAN OSA:
     # esxcli vsan cluster join -u sub_cluster_UUID
     
     For example:
     # esxcli vsan cluster join -u ########-####-####-####-########9e45
     
     
     
   • For vSAN ESA:
     # esxcli vsan cluster join -x -u sub_cluster_UUID
     
     For example:
     # esxcli vsan cluster join -x -u ########-####-####-####-########9e45
     
      
4. Verify that the host is now a part of the vSAN cluster by running the command:
   
   # esxcli vsan cluster get
   
   You see output similar to:
   
   Cluster Information
Enabled: true
Current Local Time: YYYY-MM-DDTHH:MM:SS
Local Node UUID: ########-####-####-####-########965e
Local Node Type: NORMAL
Local Node State: AGENT
Local Node Health State: HEALTHY
Sub-Cluster Master UUID: ########-####-####-####-########f17d
Sub-Cluster Backup UUID: ########-####-####-####-########dd93
Sub-Cluster UUID: ########-####-####-####-########9e45
Sub-Cluster Membership Entry Revision: 3
Sub-Cluster Member Count: 4
Sub-Cluster Member UUIDs: ########-####-####-####-########f17d, ########-####-####-####-########dd93, ########-####-####-####-########826f, ########-####-####-####-########965e
Sub-Cluster Member HostNames: esxi3.########, esxi2.########, esxi1.########, esxi4.########
Sub-Cluster Membership UUID: ########-####-####-####-########f17d
Unicast Mode Enabled: true
Maintenance Mode State: OFF
Config Generation: ########-####-####-####-########d2c2 4 YYYY-MM-DDTHH:MM:SS
Mode: REGULAR
vSAN ESA Enabled: false
    
5. In the vCenter Server, refresh the Disk Management page. The Disk group will now status as Healthy.