A lot of questions lately about vSphere Clusters across distance. I really need to learn for myself so I collected some good links.
Make sure you understand what “Only Non-uniform host access configuration is supported” means. Someone correct me if I have this wrong but your device that enables the distributed virtual storage needs to be sure that hosts in site A are writing to their preferred volumes in site A and vice versa in Site B. Probably way over simplifying it.
LINKS
http://www.yellow-bricks.com/2011/10/05/vsphere-5-0-ha-and-metro-stretched-cluster-solutions/
Big thanks to Scott Lowe for clearing the details on this topic.