Pretty soon after the RTM of Windows 2008 R2 SP1 release we were discussing a bug on the TechNet forum (Hyper-V Cluster issues after applying Win2008 R2 SP1 on a 3 node Cluster!) here. If you have a Windows 2008 R2 SP1 cluster with more than 2 nodes you get the following warning:

List Potential Cluster Disks

Disk with identifier 2sef8cdf has a Persistent Reservation on it. The disk might be part of some other cluster. Removing the disk from validation set

“Normally” you would expect such a warning if the LUN ever belonged to another cluster and it needs the old reservation cleared. To do that you would use following command on the node that throws the warning (where in this example the disk is disk 2 in disk manager/diskpart) and after making sure it is not in use anywhere else in the SAN

"cluster node clusternode1 /clearpr:2"

However this is not the cause here as were most others in this discussion. And I’m pretty no san software or MPIO software is putting a reservation on there either so what is this? A bug? Well yes, it has been confirmed by Microsoft support that is is indeed a bug an that is fix will be made available by April 18th2011 .

This was not a show stopper bug, but it could be one if you needed to add a host to a cluster and confirm all is well and supported. However if you’re certain you’ve done everything right you can choose not to run cluster validation.

I will update this blog with more information when the fix becomes available.

UPDATE:  The hotfix has become available today, April 26th 2011 as announced on the TechNet forum here:

A hotfix is now available that addresses the Win2008 R2 service pack 1 issue with Validate on a 3+ node cluster.  This is KB 2531907.  The KB article and download link will be published shortly, in the mean time you can obtain this hotfix immediately free of charge by calling Microsoft support and referencing KB 2531907. Update 27/05/2011 Here is the link: http://support.microsoft.com/kb/2531907/en-us?sd=rss&spid=14134