Your network contains two servers that have the HyperV server role installed.
You install the Failover Clustering feature on both servers.
You add both servers as nodes in the cluster.

You need to ensure that you can perform live migrations of individual virtual machines (VMs) between the nodes.

The solution must minimize the number of volumes required to host the VMs.

What should you do first?

A.
From Failover Cluster Manager, enable Cluster Shared Volumes.

B.
From Failover Cluster Manager, modify the quorum settings of the cluster.

C.
From HyperV Manager on each server, modify the default location for the virtual hard disks (VHDs).

D.
From HyperV Manager on each server, modify the default location for the virtual machine configuration files.

Explanation:
Cluster Shared Volumes, a feature available with some versions of failover clustering, simplifies the configuration and management of clustered virtual machines. With Cluster Shared Volumes, multiple clustered virtual machines can use the same LUN (disk) while still being able to fail over (or move from node to node) independently of one another.

Overview of Cluster Shared Volumes
Cluster Shared Volumes is available in versions of Windows Server 2008 R2 and of Microsoft Hyper-V Server 2008 R2 that include the Failover Clustering feature. Volumes that are configured as Cluster Shared Volumes can be accessed by all nodes of a failover cluster. Each node can open and manage files on the volumes. Therefore, different nodes can host different virtual machines that all have files on the same volume. This design has many advantages, including the following:
Easier storage management: When virtual machines share volumes, fewer LUNs need to be configured and managed to host the same number of virtual machines.

Independent failover of virtual machines: Although multiple virtual machines are sharing the same volume, each virtual machine can fail over, or be moved or migrated, independently of other virtual machines.

No drive letter restrictions: Cluster Shared Volumes do not need to be assigned a drive letter, so you are not restricted by the number of available drive letters, and you do not have to manage volumes using GUIDs.

Enhanced availability: The Cluster Shared Volumes feature is designed to detect and handle many problems that would otherwise cause the storage to be unavailable to virtual machines. This includes detecting and handling storage connection problems (Cluster Shared Volumes reroutes the storage access through another node).

Efficient use of storage: You can make better use of disk space, because you do not need to place each Virtual Hard Disk (VHD) file on a separate disk with extra free space set aside just for that VHD file. Instead, the free space on a Cluster Shared Volume can be used by any VHD file on that LUN. This reduces the total amount of space that must be set aside for expansion, and simplifies capacity planning.

Source: http://technet.microsoft.com/en-us/library/dd630633(WS.10).aspx