Hey,
I've been using TMG array for last 2-3 years and noticed few weird things. I see the more TMGs I add to the array, the more weird it becomes.. TMG is used mainly for Exchange publishing, therefore there any lots of connections and since TMG is handling the authentication, once in a while, during peak times, it fails to authenticate all requests. Probably due to LDAP limitations.
I had data center move recently and one TMG server failed. I had only four TMG server in the array and I noticed that it was performing much better, than before. Before it was Five TMG server in the arrays. Only few hundred auth errors happened during peak times.
I recovered 5th server and added it back to the array, and I see, old results. Up to the 1000 errors happened during first day.
It seems to me that TMG array of 4 members was working much better than TM away of 5 members..
Any ideas why?