How to add a host back to a vSAN cluster after an ESXi host rebuild

Products

• VMware vSAN

Issue/Introduction

This article provides steps to rebuild an ESXi host that previously participated in a vSAN (formerly known as Virtual SAN) cluster.

Environment

VMware vSAN 7.x
VMware vSAN 8.x
VMware vSAN 6.7.x

Resolution

• To rejoin the ESXi host to the vSAN cluster:
  1. Install the exact ESXi version the rest of the cluster is using, ensuring that you preserve the vSAN disk partitions.
  2. Configure the vSAN VMkernel port group on the host. For more information, see How to configure vSAN VMkernel networking (315554).
  3. Reconnect the host to the vSAN cluster in vCenter Server.
  4. Connect to one of the remaining vSAN cluster hosts using SSH.
  5. 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: 2024-10-22T01:07:35Z
     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: esxi3.########, esxi2.########, esxi1.########
     Sub-Cluster Membership UUID: ########-####-####-####-########f17d
     Unicast Mode Enabled: true
     Maintenance Mode State: OFF
     Config Generation: ########-####-####-####-########d2c2 3 2024-10-22T01:07:26.420
     Mode: REGULAR
     vSAN ESA Enabled: false
      
  6. Run one of the commands below on the newly rebuilt ESXi host using the Sub Cluster UUID identified in step 5:
     • 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
       
       
        
  7. 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: 2024-10-22T01:13:14Z
     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 2024-10-22T01:12:47.346
     Mode: REGULAR
     vSAN ESA Enabled: false
      
  8. In the vCenter Server, refresh the vSAN status view. All hosts now report the status as Healthy.