High availibility load balancing in GTM

I don't think there is a concept of 'priority groups' in GTM like there is in LTM, but Global Availability will return the first available member in the list based on the priority.

Otherwise it would probably require an iRule to determine which member that should be selected based on your specific criteria.

But I'm definitely not an expert on this-- i have setup priority based selection for a specific requirement to keep traffic to specific pool member (data center) as long as it is available. The GTM pool member points to a LTM virtual server that then provides the next layer of selection of a member (server) within that data center.