Microsoft published a documentation describing the upgrade path for clustered VMs on 2008 Failover Clusters to 2008 R2 Failover Clusters. This article describes the options that’re available for upgrading or migrating from a Windows Server 2008 installation with Hyper-V role enabled to Windows Server 2008 R2. For Windows Server 2008 Failover Clusters that’re running virtual machines, see "Upgrade guidance for virtual machines on failover clusters" section of this article. This complements other migration documentation to get you to Windows Server 2008 R2: ·General R2 Migration Guide ·Migration from R2 RC to R2 RTM ·DHCP Migration from 2003 or 2008 to R2.