Windows Server 2012 R2 Hyper-V – Generation 2 Virtual Machines

When creating a new virtual machine on WS2012 R2 Hyper-V, you will have the option to create a Generation 1 virtual machine (what has always existed in Hyper-V as just a VM) or a Generation 2 (G2) VM.  The G2 VM has the following features:

• It is free of legacy hardware.  The VM no longer attempts to pretend to be a physical machine.
• All devices run as synthetic VM Bus “hardware”
• Your VM will boot from a SCSI controller.  This means the attached OS VHDX can take advantage of SCSI/VHDX features such as TRIM, UNMAP, and hot resizing.
• The synthetic NIC can boot from the network using PXE
• The VM uses UEFI instead of BIOS.  That means it can do secure boot from GPT partitions.
• VM boots will be around 20% faster (think VDI boot storm).  OS installs will be around 50% faster.  But normal day-day operations won’t be much different.
• There are fewer devices in a VM so there are fewer VM settings

G1 VM Device Manager (left) versus G2 Device Manger (right)

I don’t expect that many people will deploy the G2 VM on WS2012 R2 as the norm, but I could be wrong.  Why?

• You cannot convert a VM between G1 and G2.  That is a UEFI and MBT/GPT thing.
• You must use 64-bit editions of Windows 8/Windows Server 2012 or later.

EDIT1:

Niklas Akerlund has blogged about how he has successfully converted a Gen1 VM into a Gen2 VM using Double-Take Move.