Thanks, Frank. You are right on the money - the best practice is to keep the number of deployed FIM service instances at a minimum. I think, we need to be a bit careful with the term "performance" in this context. The primary objective is to improve the experienced response times for specific workloads such as self-service related operations. So, a user that performs a self-service related operation might experience a better response time / performance. However, if the FIM MA were a user, that "person" might actually experience a "slower" performance. Another example might be the bulk creation of users. Whether it takes 10 or 20 seconds to bulk create 50 users from a script doesn't make a huge difference; whether it takes 10 or 20 seconds to join a group does. I've just made these numbers up to make a point... I think, carpool lanes are a good analogy. Carpool lanes can help to improve the performance of cars driving with usually at least one passenger if the other lanes are jammed; however, they don't help to improve the general throughput on a freeway. What I'm trying to get at is that you are not necessarily improving the overall performance of your FIM environment. In other words, the FIM service is typically not your performance bottleneck in your FIM environment - it is, as you have mentioned it, SQL. I can add something about this to the article if that makes it clearer. However, I would also need a better analogy because people outside the US might not know what a carpool lane is... Cheers, MarkusMarkus Vilcinskas, Knowledge Engineer, Microsoft Corporation

Markus, Great article. One thing that I've wondered about.. Obviously - one of the reasons for adding more FIM Services is for performance. I've wondered how much of the processing for various operations consumes cycles on the application server vs how much is on the SQL server side. I would imagine at some point, the SQL server would be the bottleneck and adding more Service instances wouldn't improve performance. So if only a small part of the processing is on SQL, I would be different than if lot of processing happens on SQL. Any thoughts?

FIM Experts Corner Article Wiki Page: Understanding FIM Service Partitions This is a community preview of the actual article. If you have feedback, please add it to this post. Go to the FIM Experts Corner Markus Vilcinskas, Knowledge Engineer, Microsoft Corporation