For the servers to do the same thing you need, for the servers to be part of the same Biztalk cluster. These are Biztalk front-end servers that point to the same database.
Suppose you hosted a database in a North data center, and then if the South data center goes down, the north will continue. But if the North goes down, the South stops because there is no database. Then you need a strategy to deliver your database continuously, and then switch to a copy.
To get the above work, a lot of work. Then choosing a separate Biztalk cluster on each site makes more sense. But you need to configure some routing in such a way that what is added to one cluster is transferred to another.
source share