vSAN Stretched Cluster requires exactly (1) vCenter, (1) Data Center ubject, and (1) Cluster object.  So, if you want a 4+4+1 vSAN Stretched Cluster, you'd create an 8-node vSAN Cluster with 4 nodes in each site, and a 9th witness node at a 3rd site.  See:  [URL]
Hi, We are designing our vxRail deployment and can't find specific details on the ELM.  We have 2x existing vCenter (we’ll call the VCA and VCB) connected by enhanced linked mode. Each vCenter has one datacentre site each. The deployment guide says ELM is not support in one part, while saying it's supported in another part.  We are wanting to confirm;  Can we deploy a 4x node vxRail cluster to VCA, another 4x node vxRail cluster to VCB, and use vSan stretched cluster between the 2 vxRail clusters?  Many thanks and great forum to learn vxRail [IMAGE]
vSAN stretched cluster with 2x vCenter in Enhanced Linked Mode