When configuring hosts always consider the best practices for BizTalk host separation, start with the separation of artifacts per functionality (receive, send, orchestration and tracking) then consider isolation (per application, business unit, etc), then for performance reasons and finally for reliability reasons. A good Host separation policy will help you scale your environment, ensure stability and security.
Generally it is recommended to start any BizTalk environment with at least 4 hosts, for Receiving, Orchestrations, Sending and Tracking. This follows the first principle of separation of functionality which will be easier to configure scalability and easier to control the behavior such as stopping all receives to enable an environment drain. Another important host separation technique is to have a dedicated tracking host, since tracking is a low priority sub-service if you have tracking in a very busy host it might start accumulating tracking information on the BizTalk Message Box.
Isolating artifacts with different security requirements is another reason for host separation, you can assign different Windows Groups, Users and certificates to each host creating security boundaries which will reduce the risk of running them in the same environment as other artifacts which increases the return on investment you have done in BizTalk.
You can also separate hosts for security and reliability reasons, since each host has its own set of dedicated resources such as database tables and windows services you can separate artifacts or applications that have high performance requirements that will benefit from these additional resources. If you have some unreliable artifact you can also use host separation for reducing the impact of such component (Custom Adapter, Pipeline, etc.) since if that particular host instance crashes it won’t affect anything else.
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