Migrate .Net 4.0 web application from 32bit IIS6 to 64bit IIS7

Question

We currently have an web application running on IIS6 on a 32bit machine. This application is running smooth and stable. It is built with the target "Any CPU".

Now we are copying this exact application to an 64bit IIS7 machine. We only changed the web.config, according to the IIS7 format. On the application pool we have set the "enable 32bit applications" to true.

When we put some load on this new server, the application behaves entirely different from it's old environment. We see high CPU and high memory usage. And the memory (private bytes) goes up, but does not seem to be reclaimed when the load ends.

This is not what we expected.

Did anyone encounter this same behavior? We expect it to be some mistake in the server or application configuration. Any suggestions what settings to check?

Answer 1

IIS 7 introduces the new pipe line mode "integrated" for application pools. Running your application in this mode can change the applications behaviour. If you use this mode, change it to "classic" and try again.