A traditional Nutanix cluster requires a minimum of three nodes, but Nutanix also offers the option of a one-node or two-node cluster for ROBO implementation. Both of these have a minimum requirement for the CVM to be allocated with 6 vCPUs and 20 GB memory.
Specifically for two-node, there have been several improvements in 5.10 to ensure optimal health of the cluster.Customers should upgrade to a minimum version of AOS 5.10.7 to avoid encountering any of the potential service impacting issues present in earlier releases of AOS.
The table provides a summary of improvements in the document here-
https://portal.nutanix.com/page/documents/kbs/details?targetId=kA00e0000009DaXCAU
More information about two node cluster can be found out -
ROBO implementation meaning - Short for remote office, branch office ROBO is a term used to refer to any off-site office that connects to the organization's WLAN or LAN externally.