Test Applications for Compatibility with Windows Server 2008 R2

With the introduction of Windows Server 2008 R2, x86 (32-bit) architecture hardware is no longer supported. Thankfully, Microsoft has provided WoW64 (Windows-on-Windows 64-bit), which is a subsystem of Windows capable of running 32-bit applications, and ships with all 64-bit operating systems. Through the WoW64 subsystem, Windows will be able to take care of the difference between 32- and 64-bit Windows operating systems, especially where they entail structural changes in Windows itself.

There is at least one caveat going in: Some 32-bit applications might run slower on a 64-bit OS. That consideration might be offset, on the other hand, if the application requires a lot of memory resources: In those cases it might run faster on the 64-bit OS because a 64-bit Windows OS supports more physical memory than a 32-bit OS.

Here we’ll outline a few things that can be done to ensure that applications work in Windows Server 2008 R2.

Limitations of 64-Bit OS

As with any new technology out there, there will be limitations. For 64-bit Windows operating systems, there are two primary limitations:

• 16-bit applications will not work
• 32-bit drivers/kernel-mode programs will not work.

16-bit applications are not supported in 64-bit Windows, as it will significantly decrease the performance of those programs. If the installer is a 16-bit application, while the actual application is a 32-bit application, it would be best to contact the manufacturer of the application to create a 32-bit installer to enable the application to install.

Kernel-mode applications (e.g. antivirus and drivers) which are compiled for 32-bit operating systems will most likely fail. Kernel-mode applications are low level applications, and converting the 32-bit software code to 64-bit will also decrease the system’s performance. That’s why system utility applications (e.g. antivirus, firewall, disk defragmenters) need to be recompiled to work under the new architecture.

Application Compatibility Update

One feature introduced in Windows Vista, and brought into Windows Server 2008, 2008 R2 and Windows 7 is the ability for Windows to prompt the user if an older application is tested not to work with Windows. From time to time, Microsoft will release an Application Compatibility Update through Windows Update to apprise users of the latest tested software that will not work with Windows.

Thus, my first recommendation when preparing for a migration to 64-bit Windows operating systems is to ensure that the latest updates are installed, especially any Application Compatibility Updates. The latest Application Compatibility Update can be downloaded from Windows Update or Microsoft Downloads.

Works With Windows Server 2008 R2

For all tested applications on Windows Server 2008 R2, Microsoft is providing vendors with the right to use the “Works with Windows Server 2008 R2” logo as part of the application packaging. With the “Works with Windows Server 2008 R2” logo, vendors can assure customers that the software application is indeed tested and is supported by Microsoft.

To test if a software application works on Windows Server 2008 R2, whether it is developed in-house, or downloaded or purchased from a vendor, there are two tools from Microsoft which would speed up the testing:

Microsoft Application Compatibility Toolkit 5.5

In our next article on migrating to Windows Server 2008 R2, we’ll look into how to manage a mass deployment.