Should each application have its own host instance / host instances?

Question

Should each application in BizTalk have its own host instance / host instances?

I've read various blog posts and books that it's good practice to have different host instances for different tasks, e.g. one for receive, one for send, one for orchestrations and one for tracking.

But should each application get its own receive, send, orchestration and tracking host?, or is it just one of each for all applications?

Answer 1

Short answer, probably not unless there is a particular aspect of that application that is causing a performance issue for the other applications. If that is the case you would only create a host for the particular part that is causing the issue. e.g. if it is the receive adapter you would create a host for receive locations that run under that adapter. If it is the Orchestrations for that application then create a processing host for that application for the Orchestrations of that application to run under.

Long answer from from Microsofts High Availability for BizTalk Hosts

Disadvantages of Additional Hosts

While there are benefits of creating additional host instances, there are also potential drawbacks if too many host instances are created. Each host instance is a Windows service (BTSNTSvc.exe or BTSNTSvc64.exe), which generates additional load against the MessageBox database and consumes computer resources, such as CPU, memory, and threads. Other than these, you have the following reasons for not configuring too many additional host instances:

• Several performance counters are reported per host with too much granularity. This affects the usability for the administrator who would need to traverse through a lot of data. This has a negative impact on the overall view the administrator has.

• Each host consumes considerable amount of memory that might lead to a situation of throttling and reduced performance.

• If the hosts have receive adapters that continuously perform polling, each host will poll the database at short intervals, thereby resulting in degraded performance.

Answer 2

As you're read, there are no definite rules.

Should each Application have a dedicated Host/Instance? Sure, if you've got a relatively small number of Applications for the hardware.

It's something to also consider if one Application is problematic.

Should each Application have separate Receive, Send or Orch hosts? No, not to start. If you observe a particular operation consuming a disperportionate abount of resources, then split it out.