Starting with version 4.7.100, VxRail supports vSAN 2-Node for small and Remote-Office Branch-Office (ROBO) deployments. This solution works best for environments that needs hyperconverged compute and storage with a minimal configuration. VxRail 2-Node consists of two VxRail E560 nodes and a vSAN Witness Appliance. It is recommended to deploy the Witness appliance in another site but in case of lacking another site it can be deployed in the same site as vSAN 2-Node.

There are some considerations and requirements that you need to have it in place before starting the VxRAIL 2-Node implementation.

1. VxRail supplied vCenter Server is not supported and vSAN 2-Node cluster must be connected to an external vCenter Server.
2. You need to deploy Witness Server Appliance or install Physical Witness Server in advance. In earlier article I have already described the benefits of virtual Witness appliance deployment. You can read the VMware vSAN 7.0 Witness Appliance Deployment blog post.
3. Witness appliance has 2 network interfaces. Witness Management that needs to be routable and reachable to Management Network of two node. Witness vSAN that also needs to be routable to vSAN Network of two node.
4. In VxRail 2-Node deployment the port group name you want to connect to Witness vSAN NIC , MUST name “secondaryPG” otherwise the validation would fail in the installation wizard.
5. You need to put the Promiscuous mode configuration of the port group in to “Accept” as it works like a nested VM.
6. You also need to tag VLAN for Witness vSAN on the portgroup level.
7. After the deployment is done you can add the Witness appliance in the same vCenter as you add vSAN 2-Node but under separate Datacenter.
8. After the Witness host added to vCenter you need to create a new port group for Witness vSAN traffic but it’s a requirement to be created on a separate vSwitch.

As I mentioned in point four, you need to have the secondary portgroup on vSAN Witness appliance named as secondaryPG otherwise during the deployment process you get “Resource not found secondaryPg” validation error.