Whether you’re running Windows 8.1 on your desktop and Hyper-V for a few test machines, or you’re deploying Windows 8.1 in a virtual desktop farm running Windows Server 2012 or Windows Server 2012 R2 on the back end, Hyper-V and Microsoft’s latest OS are good together — and here are some reasons why.
Generation 2 virtual machines
Windows 8.1 is designed to work within what Microsoft calls a “generation 2 virtual machine,” a new type of VM available exclusively under Hyper-V. This VM essentially strips away all pretense of virtualizing legacy PC deployments. Generation 2 VMs are UEFI-based, rather than relying on a BIOS, and there are no emulated devices. These VMs boot directly off a virtual SCSI and network adapters and also support secure boot — the preferred way to ensure only signed kernels are permitted to boot within the VM.
The only supported guest operating systems are 64-bit versions of Windows 8 and Windows Server 2012 and later. But Windows 8.1 is easier to set up within one of these VMs because it includes the necessary gen 2 keyboard driver needed to type in a product key for setup. Otherwise, you’re flying blind, or pecking at the on-screen keyboard or tearing your hair out.
Why choose a generation 2 VM over the existing VM standard? First, it gets rid of all of the goo that makes the VM look like a physical computer. Unlike in the late ’90s, people now virtualize first in most environments. Windows 8.1 has a deep knowledge of what it means to be on a VM, so there is no need for the trappings and the pretense of trying to look like a physical computer and the performance overhead that comes with that.
Deduplication for VDI deployments
If you want to run Windows 8.1 in a virtual desktop infrastructure (VDI) environment, with scores of hosts running Windows 8.1 guests in VMs that users log into as their daily drivers, then the Windows Server 2012 R2 deduplication feature can save an enormous amount of space while increasing performance.
Instead of storing multiple copies of Windows 8.1 in your guest VMs’ disk drives, which is simply wasted space, Windows Server 2012 R2 supports deduplication. It reads and then optimizes the files on a volume by storing only one copy of a file and replacing the duplicate copies with “pointers” to that single stored instance.
This deduplication feature supports open VHD or VHDX files. It can deduplicate files on a volume with running VMs so you don’t have to take your VDI farm down to begin using it. While the feature was first introduced in Windows Server 2012 Gold, the performance on the optimizer algorithm has improved, and it completes faster than it did in the previous release.
What’s the result? When the deduplication is finished, Windows can read those optimized files faster than if they were not deduplicated. And with a VDI deployment as opposed to just a typical file server, you can gain space savings up to 90% with minimal effect on performance.
Storage Quality of Service
Network Quality of Service (QoS) allows administrators to define caps for certain types of network traffic to ensure enough bandwidth exists for other activities and no one type of traffic sucks up the entire network pipe. Similarly, Hyper-V in Windows 8.1 and Windows Server 2012 R2 supports storage QoS. This feature lets you restrict disk throughput for overactive and disruptive VMs, which is great if you have a long-running process in one VM and you don’t want the overall I/O performance of your host machine dragged down. Since this feature is dynamically configurable, you can even adjust the QoS settings while the VM is running so you don’t interrupt the workload of a given VM.
Online VHDX resize
Have you ever had a VM that runs out of disk space? If you set up the VM with a fixed-size virtual disk rather than a dynamically expanding disk, this could pose a problem. However, the new Hyper-V in Windows 8.1 and Windows Server 2012 R2 allows you to increase and decrease the size of virtual hard disks of a VM while the VM is running — a hot resize, if you will. The VM in question can be running any guest OS, so there are no limitations to running Windows XP or even Linux with this feature. But the virtual hard disk file must be in the newer format (VHDX) as opposed to the older (more popular) VHD format.
Enhanced VM connect
Hyper-V in Windows 8.1 and Windows Server 2012 R2 offers what Microsoft calls “enhanced virtual machine connect,” which is the ability to use the remote desktop protocol to connect to a VM — even if the network within the VM is down. Hyper-V uses VMBus, the internal communications channel for connecting VMs to the hypervisor. It then transmits RDP over the VMBus independent of the network connection. As part of this enhanced mode, you can drag and drop files between the host and the VM, which makes use of the clipboard sharing capabilities, and you can redirect local resources like smart cards, printers and USB devices right over that VMBus connection. This makes it easier to perform troubleshooting tasks and simple administration. This enhanced mode is enabled by default if you’re running Hyper-V on Windows 8.1, but disabled by default if you are running it on Windows Server 2012 R2.