A week ago we had a discussion on twitter about a scenario which was talked about at VMworld. The scenario is one where you have two 2-node clusters and for each 2-node cluster the required Witness VM is running on the other. Let me show you what I mean to make it clear:
The Witness VM on Cluster A is the witness for Cluster B, and the Witness VM on Cluster B is the witness for Cluster A. As it stands today this is not a supported configuration out of the box. For ongoing support, it is required that users go through the RPQ process so VMware can validate the design. Please contact your VMware representative for more details.
A knowledge base article should be published on this topic soon, if and when it is published I will update this post and point to it.