What are the pros and cons of running IIS as 32bit vs 64bit on a 64bit OS?

Question

Possibly better suited for \"Rack Overflow\", but from a developer\'s point of view, what are the advantages and disadvantages of running IIS (serving both legacy classic AS

Answer 1

I've had an experience where moving from a 32bit Windows 2003 Server to a 64bit Windows 2003 Server both running IIS 6 and the performance of the ASP.NET 3.5 website was unacceptable.

The 64bit server would run a clear 2 seconds behind the 32bit one consistently.

After switching IIS 6 to run as a 32bit worker process, the performance was equal and comparable once again.

I haven't verified it, but I think it might only apply to IIS6 win2k3, as testing I've done with IIS7 x64 (Vista) and a 64bit IIS worker process seems to perform just fine.

The process to swap to the 32bit process was quite simple. Here is the KB article with the supporting details: http://support.microsoft.com/kb/894435/en-us

ASP.NET 2.0, 32-bit version To run the 32-bit version of ASP.NET 2.0, follow these steps:

1. Click Start, click Run, type cmd, and then click OK.
2. Type the following command to enable the 32-bit mode: cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 1
3. Type the following command to install the version of ASP.NET 2.0 (32-bit) and to install the script maps at the IIS root and under: %SYSTEMROOT%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i
4. Make sure that the status of ASP.NET version 2.0.50727 (32-bit) is set to Allowed in the Web service extension list in Internet Information Services Manager.

See the KB article for setting back to 64-bit.