We are currently looking at NSX for a vMSC with 12 hosts and I am not finding much documentation.
How would you go about a deciding on the management cluster configuration, I assume a new 4 node management cluster split 50/50 across the 2 metro locations and 3 NSX controllers ?
Am I missing something obvious ?
There is actually a document which might be useful for you: NSX-V Multi-site Options and Cross-VC NSX Design Guide.
I would definitely go with all 3 controllers on same site, which leads us to at least 3 management cluster nodes per site, if your budget would allow it. Of course, you can use only 2 hosts per site with a risk of loosing 2 controllers simultaneously.
Another topic is placement of Edge VMs and DLR control VMs:
If you loose 2 of 3 nsx controller, you don't have cluster majority, and the remaining one, will be on read only mode, this means that no new vni joins, because that you need to avoid the probability of this situation, deploying the 3 nsx controllers in one site is a a good way to do that and in a case of loose the site, you can re deploy the nsx controller cluster in the other site.
Other thing you need to be aware is the migrations (emotion, DRS balancing) and the ingress traffic, NSX 6.2 introduce in the cross site deployment a feature that allow to optimise egress traffic, but with the ingress traffic, you maybe, would have network traffic trombone.
VCP5-DCV, VCP6-DCV, VCP6-NV, VCAP-DCA/DCD, VCIX-NV, VCI