Here’re the top issues for Windows Server 2008 Failover Cluster:
1. Hyper-V rollup fix – A rollup fix was released to allow for multiple highly available VM's (and their *.vhd files) to be placed on a single 'Physical Disk' resource. The fix for this issue is available for download directly from within the KB article: http://support.microsoft.com/kb/951308.
2. Storage hardware does not support SCSI 3 Persistent reservations – All of these issues are confirmed by running the Cluster Validation tests. Most scenarios involved adding disks to an established cluster without running validation test and having problems getting the disks added successfully. Many hardware vendors have settings in BIOS, firmware updates available to support SCSI 3 Persistent reservations. More information about this can be found at: http://technet.microsoft.com/en-us/library/cc771259.aspx#PersistentReservation and http://support.microsoft.com/kb/947710.