32 bit mode on a 64 bit machine? Why?

The problem

If you install SalesLogix on a 64 bit machine (Windows server of course), you are told that you need to change your application pool mode to “classic.” This instruction is on page 93 of the current implementation guide. It seems that this would be a huge hindrance to performance for your website. That isn’t the case with this particular setting. The Managed Pipeline mode tells IIS how to handles requests. By default IIS 7 will use a single pipeline for all code and this pipeline is tightly integrated with ASP.NET, which I assume means better/faster. This mode does not have anything to do with memory instead it adds the ability for IIS to run some legacy modules.

What about the Allow 32 bit applications setting? Same deal here, we have some modules that will not run in 64 bit mode like the provider and groupviewer. So does this mean in 32 bit mode my website is only getting 2 gigs of Ram? yes it does but not really.

Good practice?

Each application pool is assigned that 2 gigs of memory. You can place SData, SlxClient, and processhost in their own app pools. The same goes for any other virtual directory. In their own app pool each virtual directory will get its own 2 gigs of memory. Not too bad, but you can always up that to 4 gigs with a registry setting.

An easy solution? Well it isn’t necessarily a solution, but an easy way to get your website some more memory. You need to match these application pool settings in Application Architect since AA will by default use the same app pool for all portals.

I bet the fix is to get those modules rewritten or modified so they are not 32 bit or classic mode dependent.

But wait there is more

According to Stuart Carnie who ran a dumpbin on w3wp.exe on a 64 bit machine w3wp is large address aware and does get 4 gigs be default.

I think we have a good solution worked out. Is this how you do it? Is my explanation off somewhere? I am not an expert in IIS by any means, so please add your comments!