A: The question of pagefile size in Windows Server 2012 Hyper-V is a tricky one and similar to a problem encountered in earlier versions of Windows.
Typically, the pagefile matches the size of physical memory with some additional value. However, in the case of Hyper-V, the actual parent partition, the OS installed on the hardware, isn't using most of the memory--the virtual machines (VMs) are using the memory.
If you have a Hyper-V server with 128GB of RAM you likely don't want to have a 128GB pagefile since that host OS isn't using it. There's no absolute answer without doing data discovery on each server and looking at the actual memory commit on the hosts. However, many people use a value of around 6GB for servers with large amounts of memory, which should be sufficient for most scenarios. This TechNet blog has some interesting points that are worth considering.