Hot Add/Remove of Storage in Hyper-V (Windows 2008 R2)
One of the new features in the next release of Hyper-V is the ability to hot add/remove storage. However, this feature does not apply to storage connected to the IDE Controller. The ability to hot add/remove storage is limited to disks connected to the SCSI Controller i.e. VHDs and Pass-Through disks. Note that the ability to hot add/remove the storage controller itself is not supported, so you need to ensure that the Guest Partition is configured with a SCSI Controller first.
Patrick Lownds