Windows Server cluster installations have typically required shared storage, meaning that all nodes in the cluster must be able to see the storage. SQL Server Denali uses Windows Server Clustering for some of its new high availability technologies, but requires that there be a single Windows Server Failover Cluster (WSFC) between sites. The problem with that is that if you have two sites that are separate geographically, there is no shared storage. When you attempt to add the remote nodes, th clustering validation tool will fail with errors.
The Windows team has released a fix for this so that Windows clusters can now support Asymmetric Storage – some nodes can see some of the storage, and some nodes can see other storage. Clustering validation will still show warnings, but the validation will pass and allow you to add the remote nodes to the cluster.
Here is an example of the warnings that are shown. There will be a warning for each disk:
Windows Server 2008 R2 requires SP1, and Windows Server 2008 requires a hotfix. More information about this can be found in the following KB article: http://support.microsoft.com/kb/976097.