When you initiate an shutdown on a failover cluster node the cluster service issues an offline/failover of the owned cluster groups. in case of virtual machines it would initiate an quick migration to next configured node.The timeout values can be controlled in R2 clusters:
This property is also exposed as the ShutdownTimeoutInMinutes property of the MSCluster_Cluster WMI class.
Note If the Hyper-V role is installed, the default time-out value is calculated based on the size of physical memory, using a ratio of 100 minutes / 64 GB. The minimum computed value is 20 minutes
This is only applicable for Windows 2008 R2 failover clusters!