Have you seen how easy it is to move running Virtual Machines from one physical server host to another physical machine? In this quick video you will see how easy it is to move a running VM from one hyper-v host to another with no downtime.
You will see an old school DOS game continues to run while being move from one host to another. These are two stand alone machines. First the hard disk data is synchronized then the ram is synced lastly everything is moved over to the new machine and deleted from the old. Shared nothing live migration is a fantastic technology that allows you to make changes to the hardware with no downtime for your VMs because you move them to other hosts!
Check it out. It's worth your time.