Before you shut down, reboot, or disconnect a host that is a member of a Virtual SAN cluster, you must put it in maintenance mode. When you place a host in maintenance mode, you can select a specific evacuation mechanism. Note that when any member node of a Virtual SAN cluster enters maintenance mode, the cluster capacity is automatically reduced as the member node no longer contributes storage to the cluster.


Check that your environment has the capabilities required for the option you select.


  1. Right-click the host and select Enter Maintenance Mode.
  2. Select one of the evacuation modes and click OK.
    Option Description
    Ensure accessibility This is the default option. When you power off or remove the host from the cluster, Virtual SAN ensures that all accessible virtual machines on this host remain accessible. Typically, only partial data evacuation is required.

    Select this option if you take the host out of the cluster temporarily, for example, to install upgrades, and plan to have the host back in the cluster. This option is not appropriate when you permanently remove the host from the cluster.

    Full data migration Virtual SAN evacuates all data to other hosts in the cluster and maintains or fixes availability compliance for the affected components in the cluster. This option results in the largest amount of data transfer and consumes the most time and resources. Select this option if you plan to migrate the host permanently. When evacuating data from the last host in the cluster, make sure you migrate the virtual machines to another datastore and then place the host in maintenance mode.
    Note: The host will not enter maintenance mode if a virtual machine object that has data on the host is not accessible and cannot be fully evacuated.
    No data Migration Virtual SAN does not evacuate any data from this host. If you power off or remove the host from the cluster, some virtual machines might become unaccessible.