Explanation/Reference:
Explanation:
Procedure
1 Navigate to the Virtual SAN cluster in the vSphere Web Client.
2 Click the Manage tab and click Settings.
3 Under Virtual SAN, click Fault Domains and Stretched Cluster.

4 Click the Create a new fault domain icon ( ).
5 Type the fault domain name.
6 From the Show drop-down menu, select Hosts not in fault domain to view the list of hosts that are not assigned to a fault domain or select Show All Hosts to view all hosts in the cluster.
7 Select one or more hosts to add to the fault domain.
A fault domain cannot be empty. You must select at least one host to include in the fault domain.
8 Click OK.
The selected hosts appear in the fault domain
Reference: https://pubs.vmware.com/vsphere-60/index.jsp?topic=%2Fcom.vmware.vsphere.virtualsan.doc
%2FGUID-C365ACE8-7485-4463-A12C-71D1917A4930.html