32-bit .NET on 64-bit IIS? There’s an App Pool for That!

A lot of Port80 customers are still in the process of making a couple of related platform transitions — from 32-bit to 64-bit server hardware, and from IIS 6 (Server 2003) to IIS 7 (Server 2008). For those who are doing so, and facing the problem of what to do about your legacy .NET applications that use 32-bit DLLs, you’ll be glad to discover that Server 2008 is your friend.

With Server 2003, on 64-bit hardware, you had to choose whether to run all your IIS worker processes in 32-bit or 64-bit mode:  It was all or nothing.  But what you’ll find when you make your Server 2008 migration is that you now have the flexibility to run some Application Pools in native 64-bit mode, and others in 32-bit mode.

That’s extremely handy for managing the transition for legacy .NET apps that may rely on 32-bit DLLs. Since it lets you move sites and apps into the new 64-bit environment little by little. And best of all it’s trivial to set up in the IIS 7 Manager (no more futzing with the metabase). Rakki Muthukumar has a post from way back in 07 that lays it all out for you (yes, this technology has been available right from the get go with Server 2008).
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And, in case you’re wondering, we’re aware of the need to support this “mix-mode” scenario (part 32-bit, part-64) in our Port80 products as well.  httpZip already has support for mix-mode in Server 2008 and the same level of support is coming soon to CacheRight and LinkDeny as well.

/P80