VxRail software version 4.7.100 introduces support for a fixed 2-node configuration that uses direct connection between the two nodes for cluster operations. With its small footprint, it can be an appropriate, cost-effective solution for locations with limited space and workload requirements. The support requires that the configuration to be a brand-new deployment which means existing clusters cannot utilize node removal to convert into a 2-node configuration. Cluster expansion is not supported therefore this solution should be targeted for specific use cases. Only the VxRail E560 and E560F are supported in a 2-node cluster. Users can still benefit from automated lifecycle management.
Figure 55. VxRail 2-node cluster
The configuration consists of the two nodes directly connected and a Witness to provide quorum for the cluster. The direct connection is for the vSAN and vMotion traffic. The Witness is a virtual appliance installed on an ESXi host which must reside outside of the 2-node cluster, i.e. in another datacenter or a physical host in the same rack/location. The Witness has individual connections to both nodes which requires VLANs to separate Witness management traffic from vSAN traffic. The configuration only supports mirroring (FTT=1). Witness host is used as the tiebreaker. Each node and the Witness is an individual fault domain for a total three in the cluster.
A special workflow in the First Run experience is used to deploy the 2-node cluster. The workflow includes the setup of the Witness appliance and Witness traffic separation. The configuration must use a customer-supplied vCenter for management. With only two data nodes in the cluster, users need be cognizant of the cluster load to prevent data unavailability in case of a node failure and a single node servicing the entire cluster workload.
The 2-node cluster supports per-socket vSAN Standard, Advanced, and Enterprise license editions. Refer to the vSAN Licensing Guide for more details.
For more information about this configuration, refer to the VxRail Technical Deck.