You have 3 Hyper-v R2 servers populated with 32GB, you run on each 15 virtual machines with 2GB of memory each, leaving 1GB free and 1GB for the parent.
Now you need to patch the host but facing a little BIG problem, you cannot live migrate any VM because you just don’t have the available memory to accomodate 15 virtual machines on the other 2 Hyper-V R2 servers… I wish I had memory over commit damn it!
So what now!? Well go to your hardware vendor, he will be so happy to help you out with a brand new server with 32GB of memory… Who said Microsoft Live Migration was for free 😉
Sure if you have many more Hyper-V R2 servers, you can distribute the VMs more easily unless your consolidation ratio is very high, like the ISV’s use to do for instance.
But no worries, I trust Microsoft to make it better and better…