New failover cluster APIs have been implemented in Windows Server 2008, and these APIs may pose interoperability issues with earlier versions of Windows

In Windows Server 2008, a new set of platform APIs has been implemented to provide better functionality, better scalability, and easier manageability for clustering environments. The manageability aspect includes remote management. However, this new set of failover cluster APIs also poses interoperability issues with earlier versions of Windows.

The new set of failover cluster APIs in Windows Server 2008 implements the following changes:

�	The backup APIs have been removed in Windows Server 2008. You must now use the Volume Shadow Copy Service (VSS) writer to reach this backup functionality in a clustering environment. Additionally, several new APIs have been added, although the pre-Windows Server 2008 APIs should still function.
�	Cluster Automation Server (MSClus) is a COM interface that has been deprecated in Windows Server 2008. None of the new APIs are exposed through MSClus, and this interface will be removed completely in future versions of Windows. Vendors should begin migrating away from MSClus, although MSClus code may still function correctly in Windows Server 2008.
�	The Windows Management Instrumentation (WMI) provider has been improved in Windows Server 2008, and it now enjoys feature parity with the failover cluster APIs.

Note Because of a core protocol change in Windows Server 2008, you cannot call failover cluster APIs from earlier Windows clients to Windows Server 2008 clusters. Therefore, the new failover cluster APIs cannot be called from Windows XP or from Windows Server 2003. Currently, the cluster APIs can be called against a Windows Server 2008 cluster only from Windows Vista Service Pack 1 (SP1) or from Windows Server 2008.