A two-node vSAN cluster has two hosts at the same location. The witness function is performed at a second site on a dedicated virtual appliance.
Two-node vSAN clusters are often used for remote office/branch office environments, typically running a small number of workloads that require high availability. A two-node vSAN cluster consists of two hosts at the same location, connected to the same network switch or directly connected. A third host acts as a witness host, which can be located remotely from the branch office. Usually the witness host resides at the main site, with the vCenter Server.
A single witness host can support up to 64 two-node clusters. The number of clusters supported by a shared witness host is based on the host memory.
