1. Generation 2 VMs—I think the most forward thinking enhancement in the new Windows Server 2012 R2 Hyper-V is the new generation 2 virtual machines (VMs). These new generation VMs are built exclusively to be run only as VMs. They leave all of the legacy VM baggage behind. There’s no BIOS and no legacy devices. The new VMs are UEFI-based. They can boot off virtual SCSI or network adapters. The new generation 2 VMs can only run the Windows 8 or Windows Server 2012 x 64 operating systems, or higher.
2. Full Remote Desktop support—The new release of Hyper-V also provides full remote-desktop capabilities—even when the network is no available. It does this by integrating the Remote Desktop support into the Hyper-V management console. The connection to the VM is made over the VMBus interface.
3. Automatic Activation of VMs—It was a hassle when Microsoft first implemented it and activation remains a hassle today. However, the new Hyper-V makes life for guest VMs a bit easier by providing automatic activation.
4. Faster live migration—The new Hyper-V release also features two ways to achieve faster live migrations. First, it enables the VM memory and data to be compressed when performing the live migration. This compression can enable up to a 2x performance improvement for live migration. In addition, live migration can also take advantage of the high performance SMB Direct feature for improved performance on high speed networks.
5. Online VHDX resize—Another nice improvement is the ability to increase and decrease and decrease VHDX files with no interruption of end users services. This new feature is limited to the new VHDX format and isn’t available for the older VHD format.
6. Storage Quality of Service (QoS)—Windows Server 2012 R2 Hyper-V also introduces the ability to provide QoS for storage. Storage QoS gives you the ability to throttle back I/O intensive VMs making sure that one or two overly active VMs don’t monopolize the host storage subsystems.
7. Live VM export—The new Hyper-V also provides the ability to perform live exports of running VMs. This can help you to more easily clone and move VMs. The export process takes a snapshot of the VM’s current state.
8. Extended Replica for DR—Hyper-V Replica was one of the most popular features in Windows Server 2012. With Windows Server 2012 R2 Hyper-V you can now replicate a target VM that has been replicated from another Hyper-V. This allows a hosting company who might be acting as a Hyper-V Replica target to backup or replicate the VM for redundancy. In addition, Windows Server 2012 R2 Hyper-V also allows you to control the interval which the replication logs are sent from the source to the replica target.
9. Support for USB pass-through—While USB pass-through isn’t a huge deal, it’s definitely something that almost every Hyper-V administrators has wanted for a long time. USB pass-through allows you to attach a USB device to the Hyper-V host and then access that USB device from the Hyper-VM guest VMs. This can be very handy for installing software or quickly copying data into your Hyper-V VMs.
10. Windows Azure IaaS compatibility—Windows Azure IaaS uses exactly the same virtualization as Windows Server 2012. This means there’s 100 percent complete compatibility for running VMs both on-premise and in Windows Azure IaaS. If you have network virtualization in place then you can even seamlessly live migrate your on-premise Windows Server Hyper-V VMs to Windows Azure and back again.