This is my current scenario: there are two existing servers in a stand-alone array - TMG01 and TMG02, and over in a DR site there is a new server (TMG03) that is in the process of being built. To comply with DR, all 3 servers must have their configurations up to date, however there is no direct communication allowed between the two DMZs, so simply adding to the new server as an array member is not possible.
In this post I will be installing a TMG Array as a “back firewall” behind a hardware firewall. The Array will consist of two virtual servers, TMG01 and TMG02 which each have 3 NICs. One NIC will be dedicated to the LAN network, accessible internally. One NIC will be dedicated to the DMZ network, accessible to the outside world on a static mapped IP. The third NIC will be a dedicated intra-array communications NIC as per Microsoft’s recommendation.