Explanation/Reference:
Explanation:
Ref: http://technet.microsoft.com/en-us/library/dn265980.aspx
http://technet.microsoft.com/en-us/library/dn281956.aspx
Note: Disk sharing can only be set on VHDX disks.
Shared virtual hard disk functionality in guest failover clusters exclusively uses the .vhdx file format.
Although the shared virtual hard disk must use the .vhdx file format for the data drive, the operating system disk for a virtual machine can use either the .vhd or the .vhdx file format.