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