First look: Windows Server 2012 R2 Hyper-V shines on

Generation 2 VMs can boot from a SCSI virtual hard disk or SCSI DVD or over the network. These new virtual devices deliver significantly faster boot times. You also get the ability to resize any VHDX attached to a SCSI controller even when the VM is running. This was not the case with previous versions of primary VM disk drives.

Automatic provisioning
In previous versions of Hyper-V, every time you created a new virtual machine you were required to license it separately from the host machine. With Windows Server 2012 Datacenter R2, this is no longer the case. Every new VM running Windows Server 2012 will automatically be provisioned as licensed. This new license type is called an Automatic Virtual Machine Activation (AVMA) key for Datacenter Server. Guest virtual machines must be running Windows Server 2012 R2 Datacenter, Standard, or Essentials in order to use the AVMA key. The end result is a faster provisioning process for new VMs and the elimination of the need to connect to the Internet to activate a new installation.

PowerShell 4.0
The latest version of PowerShell includes a significant number of new cmdlets supporting Hyper-V. In addition, the default execution policy setting on Windows Server 2012 R2 Preview is now set to RemoteSigned. Previous versions had this set to Restricted, which would not allow any scripts to run without first changing the policy. This change, while minor, will save quite a bit of time and frustration on the part of newbie administrators. The following are a few new cmdlets specifically related to Hyper-V.

Measure-VM. This new cmdlet will gather a number of resource measurements for your perusal. It's important to point out that resource metering is not turned on by default. To enable it on all your VMs, simply type the following at a PowerShell prompt with administrator privileges:

Get-vm| Enable-VMResourceMetering

This returns a nice list of statistics, including AggregatedAverageNormalizedIOPS for measuring overall disk performance.

Copy-VMFile. This new cmdlet allows administrators to copy files to a running VM without using a network connection. It does require Guest Services to be enabled on the Integration Services property page of the VM. A PowerShell cmdlet is also available to accomplish the same task:

Enable-VMIntegrationService

Online VM export
With Hyper-V R2, you can now perform a VM export on a running virtual machine or a virtual machine checkpoint. You can accomplish this from Hyper-V Manager or by using the PowerShell cmdlet Export-VM or Export-VMSnapshot. This requires a Windows Server 2012 R2 host, as this feature is not supported on previous versions.

Shared virtual disks
Clustering is typically considered a capability of physical hardware. It's primarily intended to provide failover capability for highly available (HA) resources. Hyper-V in Windows Server 2012 R2 includes support for shared virtual hard disks (VHDX) hosted on either an SMB 3.0 Scale-Out File Server or a Cluster Shared Volume (CSV) to provide physical redundancy for the storage. This eliminates the need for costly SAN hardware to build out an HA solution using VMs and commodity storage. One thing you won't be able to do with Shared Virtual Disks is implement Storage QoS.