Written by Michael Cherry

As with all OS updates, new and updated features in Windows Server 2008 R2 require testing to ensure compatibility with existing applications that will be migrated to the new OS. Some Microsoft applications may require a specific version or service pack that might not yet be available. Consequently, organizations need to plan deployment of Windows Server 2008 R2 carefully so that they do not get in a situation where a key application is not available. Although Server Core was updated to support the .NET Framework, infrastructure services running on Server Core may be the easiest to verify and deploy.

What Needs to Be Tested

Applications that will require compatibility testing can typically be divided into three groups:

• Microsoft server applications (by version and service-pack level)
• Third-party applications (such as non-Microsoft database engines, utilities, and security tools)
• In-house or custom line-of-business applications.

Although organizations can leave it to Microsoft and other software vendors to test their own applications, customers will want to verify the status of their vendors' applications and plan to deploy compatible versions on Windows Server 2008 R2. In addition, customers and ISVs will want to use the free downloadable application compatibility and logo testing tools provided by Microsoft to determine whether packaged and custom applications will run on Windows Server 2008 R2.

Microsoft Server Application Status

According to Microsoft, most Microsoft Server applications will support Windows Server 2008 R2 within 180 days of general availability (Based on the general availability date of Oct. 22, 2009, 180 days would be Apr. 20, 2010).

As was the case with the release of Windows Server 2008, some Microsoft applications still in Mainstream support are not supported on Windows Server 2008 R2, and not all versions or service-pack levels of other applications are supported. More often than not, only one specific version at a specific service-pack level is supported, even if earlier versions run on the OS. (For a summary, see the chart "Microsoft Applications and Windows 2008 R2".)

Although code and service changes in Windows Server 2008 R2 did not change the architectural foundations of the OS, even minor changes require at least some degree of compatibility testing. Since switching to a series of alternate major and minor releases, the Windows Server team has generally met its estimated release dates, meaning that other Microsoft product teams and third parties could have started compatibility testing of their current and new versions during the beta or release candidate stage of development and testing. But even if the OS is available for testing, such compatibility testing for already shipping versions often takes a back seat to the development and testing of the next release of their product.

In general, Microsoft product groups focus on making at least the latest shipping version of their products work on the latest version of Windows Server, although customers may have to wait to get that level of support. Depending on where a product is in its life cycle, only a future version may be supported. This is the case with Windows Server 2008 R2 and Exchange—only the next version, Exchange 2010, will run on Windows Server 2008 R2.

Few product groups are willing to devote resources to making an older version of their product compatible with a new Windows Server release, even if the product is still in Mainstream support. This shows, once again, that organizations should take the Mainstream support designation with a grain of salt—it does not provide any assurance that the Mainstream product will be compatible with a Windows OS released later in the product's life cycle.

Resources

The latest version of the Microsoft applications supported on Windows Server 2008 R2 is available at www.microsoft.com/windowsserver2008/en/us/supported-applications.aspx.

Resources for developers designing applications for Windows Server 2008 R2 are located at msdn.microsoft.com/windowsserver.

The free compatibility test tools, which measure an application's compatibility and compliance with the Windows Server Logo requirements, can be downloaded from www.microsoft.com/windowsserver/appcompat.