As title says, the ganglia page is defaulting to cluster report, which is quite ugly as it is attempting to mesh the 2 clusters together. Both ganglia/?c=kvmsrvGrid and ganglia/?c=unspecified work fine.
I'd like it to look like this: http://monitor.millennium.berkeley.edu/?m=&r=hour&s=descending&hc=4
Instead it looks more like this (with kvmsrvGrid): http://ganglia.millennium.berkeley.edu/infrastructure/?c=Management%20Servers
gmetad.conf:
data_source "unspecified" localhost:8649
data_source "kvmsrvGrid" kvmsrv5:8650 kvmsrv4:8650
gridname "unspecified"
edit: Ganglia version 3.1.2
Finally figured out the answer. If you only have one cluster it defaults to this cluster view. And for some reason a cluster named "unspecified" doesn't count toward the number. Renaming "unspecified" to "servers" fixed the grid view.
It seems that using the same name for gridname and data_source actually causes the described behaviour. I also had the same name, which was different from "unspecified" and changing the gridname value solved the issue. So to sum up to solve the problem use different names in the two parameters and changing any one would do.