if you download 2.2.2 it has this exact example shipped
Is the clustered-static-discovery example the one you are refering to? it appears to use an element <static-connectors> that is not present in 2.1.2 (which I'm using via Torquebox).
What is the equivelent to this in 2.1.2 hornetq-configuration.xml?
Also, is that example symmetric? it appears server1-3 are connecting to server0 only.
Yes, that example should be symmetric. If you take a look at the clustered-static-oneway example you'll see that it uses <static-connectors allow-direct-connections-only="true">. As I understand it, allow-direct-connections-only defaults to false and when false it means the cluster will discover other members without needing a <connector-ref> element for each member of the cluster. I don't think any harm would come from adding the extra <connector-ref> elements for each server though.