After you upgrade the vCenter Server, the next task for the Virtual SAN cluster upgrade is upgrading the ESXi hosts to use the current version.

If you have multiple hosts in the Virtual SAN cluster, and you use vSphere Update Manager to upgrade the hosts, the default evacuation mode is Ensure data accessibility. If you use this mode, and while upgrading Virtual SAN you encounter a failure, data can become inaccessible until one of the hosts is back online. For information about working with evacuation modes, see Place a Member of Virtual SAN Cluster in Maintenance Mode

Before you attempt to upgrade the ESXi hosts, review the best practices discussed in the vSphere Upgrade documentation. VMware provides several ESXi upgrade options. Choose the upgrade option that works best with the type of host that you are upgrading. For more information about various upgrade options, see the vSphere Upgrade documentation.


  • Verify that you have sufficient disk space for upgrading the ESXi hosts. For guidelines about the disk space requirement, see the vSphere Upgrade documentation.
  • Verify that you are using the latest version of ESXi. You can download the latest ESXi installer from the VMware product download Web site at
  • Verify that you are using the latest version of vCenter Server.
  • Verify the compatibility of the network configuration, storage I/O controller, storage device, and backup software.
  • Verify that you have backed up the virtual machines.
  • Use Distributed Resource Scheduler (DRS) to prevent virtual machine downtime during the upgrade. Verify that the automation level for each virtual machine is set to Fully Automated mode to help DRS migrate virtual machines when hosts are entering maintenance mode. Alternatively, you can also power off all virtual machines or perform manual migration.


  1. Place the host that you intend to upgrade in maintenance mode.
    You must begin your upgrade path with ESXi 5.5 or later hosts in the Virtual SAN cluster.
    1. Right-click the host in the vSphere Web Client navigator and select Maintenance Mode > Enter Maintenance Mode.
    2. Select the Ensure data accessibility or Evacuate all data evacuation mode, depending on your requirement, and wait for the host to enter maintenance mode.
      If you are using vSphere Update Manager to upgrade the host, or if you are working with a three-host cluster, the default evacuation mode available is Ensure data accessibility. This mode is faster than the Evacuate all data mode. However, the Ensure data accessibility mode does not fully protect your data. Host failure during maintenance mode operations can cause some data to become inaccessible until one of the hosts is back online.
  2. Upload the software to the datastore of your ESXi host and verify that the file is available in the directory inside the datastore. For example, you can upload the software to /vmfs/volumes/<datastore>/
  3. Run the esxcli command install -d /vmfs/volumes/53b536fd-34123144-8531-00505682e44d/depot/ --no-sig-check. Use the esxcli software VIB to run this command.
    After the ESXi host has installed successfully, you see the following message:

    The update completed successfully, but the system needs to be rebooted for the changes to be effective.

  4. You must manually restart your ESXi host from the vSphere Web Client.
    1. Navigate to the ESXi host in the vSphere Web Client inventory.
    2. Right-click the host, select Power > Reboot, click Yes to confirm, and then wait for the host to restart.
    3. Right-click the host, select Connection > Disconnect, and then select Connection > Connect to reconnect to the host.
      To upgrade the remaining hosts in the cluster, repeat this procedure for each host.

      If you have multiple hosts in your Virtual SAN cluster, you can use vSphere Update Manager to upgrade the remaining hosts.

  5. Exit maintenance mode.

What to do next

  1. (Optional) Upgrade the Virtual SAN disk format. See Upgrade Virtual SAN Disk Format Using RVC.
  2. Verify the host license. In most cases, you must reapply your host license. You can use vSphere Web Client and vCenter Server for applying host licenses. For more information about applying host licenses, see the vCenter Server and Host Management documentation.
  3. (Optional) Upgrade the virtual machines on the hosts by using the vSphere Web Client or vSphere Update Manager.