Windows Server 2012 R2 Hyper-V features: Generation 2 virtual machines

Brien Posey

What impact will the new Hyper-V Generation 2 virtual machines have on data storage?

Brien PoseyOne of the boldest new Windows Server 2012 R2 Hyper-V features is the ability to create Generation 2 virtual machines (VMs). Generation 2 VMs offer a number of exciting capabilities, many of which are directly related to storage.

In case you haven't heard about Generation 2 virtual machines, they are designed to be more efficient than first-generation VMs. They do not use emulated hardware, but instead make use of a fully exposed virtual bus. However, this change limits your operating system choices. In addition, Generation 2 VMs only support 64-bit editions of Windows Server 2012, Windows Server 2012 R2, Windows 8 or Windows 8.1.

Generation 2 VMs still make use of VHDX-based virtual hard disks, but the guest operating system now treats the VHDX file as a SCSI disk. Incidentally, Generation 2 VMs also support Preboot Execution Environment (PXE) booting.

From a storage management standpoint, the most significant benefit to using Generation 2 virtual machines is that they make it possible to dynamically resize storage on an as-needed basis. VHDX files can be expanded or compacted while the VM is running. This holds true even for boot VHDX files.

Other Hyper-V features available with Generation 2 virtual machines include the ability to clone or export a VM while it is running. A virtual machine can be cloned in its current state, or the cloning process can be based around a VM checkpoint. The checkpoint Hyper-V feature has replaced the Hyper-V snapshot feature.

Generation 2 VMs do not use emulated IDE controllers, but rather communicate with VHDX files using native SCSI commands. This leads to a significant increase in VM performance. Windows Server 2012 R2 is still in development, so no official performance benchmarks exist yet, but my own observations have been that Generation 2 VMs seem to boot approximately 30% faster than a Generation 1 VM running on comparable hardware. I have also seen a major performance improvement when it comes to OS installation. On my test servers, the OS installed on a Generation 2 VM in less than half the time that it took to install on a Generation 1 VM.

About the expert: 
Brien Posey is a Microsoft MVP with two decades of IT experience. Before becoming a freelance technical writer, Brien worked as a CIO for a national chain of hospitals and health care facilities. He has also served as a network administrator for some of the nation's largest insurance companies and for the Department of Defense at Fort Knox.

There are Comments. Add yours.

 
TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to: