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I’m a big fan of the changes to clustering in Windows 2008, especially the new cluster support policy which is a big improvement over the HCL used for cluster validation in Windows 2000 and 2003. The HCL has been replaced by a Validation Test and a supported solution requires a Windows 2008 cluster to pass a Cluster Validation Test.
I was recently building a Windows 2008 cluster to run SQL Server 2005 which consisted of two HP DL585 servers and storage provided by an HP EVA 4000 when I ran into a validation failure. The cluster validation test flagged a network configuration problem. The validation report showed a failure for the cluster based on a duplicate IP address:
Verifying that there are no duplicate IP addresses between any pair of nodes.Found duplicate IP address fe80::497:2557:ad2d%30 on node srv1.domain.com adapter Local Area Connection* X and node srv2.domain.com adapter Local Area Connection* X.
Following some research on the web - I found I wasn’t the first to experience this validation failure. The duplicate IP address is caused by Teredo which is a technology to provide IPv6 devices with Network Address Translation (NAT) over IPv4 networks. Teredo was installed but disabled in Server 2003, and Windows XP, but is enabled by default in Vista and Server 2008. Cluster validation fails because Teredo adapters have identical IP addresses - and duplicate IP addresses aren’t supported in a cluster.
Providing you don’t require NAT for IPv6 devices – the easiest way to overcome this problem is to disable the Teredo device in Device Manager (first choose ‘Show Hidden Devices’ from View menu).
There’s a recent blog post from the Cluster team and a thread Elden Christiensen mentioning this same problem.
Justin Langford
Coeo - SQL Server Consulting | Remote DBA | Dedicated Database Engineering