Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine the Microsoft Windows® service pack version installed on each node in the cluster:

HKEY_LOCAL_MACHINE\Cluster\Nodes\<Node Number>\CSDVersion

If the Exchange Server Analyzer finds the value for CSDVersion on the second or subsequent node in the Exchange cluster different from the value for CSDVersion on the first node in the Exchange cluster, an error is displayed.

This error indicates that the nodes in this Exchange cluster are not running the same level of Windows service pack. It is recommended as a best practice that all nodes in an Exchange cluster run the same level of operating system and service pack.

To resolve this problem, you must upgrade all nodes to the same operating system and service pack. To minimize downtime, you can perform a rolling upgrade of your cluster.

To correct this warning

  1. Review the instructions for performing a rolling upgrade of a cluster, by reading the Microsoft Knowledge Base article 811272, "How to Perform a Rolling Upgrade of Windows Server 2003 Server Clusters" (

  2. Review the article, "Windows 2000 Clustering: Performing a Rolling Upgrade" (

  3. Perform a rolling upgrade of each node whose CSDVersion value is different from the first node in the cluster.

For information about alternative procedures, see "Alternatives to rolling upgrades" (