Some New Features and Enhancements in Windows 2012 R2 Preview.

Content in this post applies specifically to Windows Server 2012 R2 Preview is preliminary and subject to change in future releases.

Enhanced Session Mode in Windows 2012 R2 Preview

The previous versions of Hyper-V only provided redirection of the VM Screen, Keyboard, Mouse and some limited copy/paste functionality. Additional redirection abilities depended on Remote Desktop Connection to virtual machine which require a network to the Virtual Machine.

The Virtual Machine Connection tool in Windows Server 2012 R2 Preview Hyper-V now support redirection of local resource similar to the Remote Desktop Connection session. The enhanced session mode connection uses virtual machine buss (VMBuss) to connect to the Remote desktop connection session so no network connection to the virtual machine is required.

The Virtual Machine Connection tool in Windows Server 2012 R2 Preview Hyper-V is disabled by default.

To enable, Right click on Hyper-v server under Hyper-V manager and then select Hyper-V Settings,

Enhance Session1

Select Enhanced Session Mode policy and then enable Allow enhanced session mode.

Enhance Session2

This setting affects all virtual machines running on the server running Hyper-V.

The following guest operating systems support enhanced session mode connections:

  • Windows Server 2012 R2 Preview
  • Windows 8.1 Preview

The following local resources can be redirected when using the Virtual Machine Connection tool.

  • Display configuration
  • Audio
  • Printers
  • Clipboard
  • Smart cards
  • USB devices
  • Drives
  • Supported Plug and Play devices

Enhance Session

Additionally the Remote Desktop Service needs to be running and the user account you be using to log on to the virtual machine needs to be a member of the Remote Desktop Users local group or the local Administrators group.

A proper USB device redirection in Hyper-V environment is still not available, however enabling the Enhanced session mode will be much useful in following scenarios:

  • Accessing physical drives without the need for a network connection to the virtual machine.
  • Login to the virtual machine via smart card
  • Printing from a virtual machine to a local printer
  • Adjusting display size to match with screen resolution.
  • Testing application running in virtual machine that require USB redirection without need to use remote desktop connection.

Cross-version Live Migration

Live migration was introduced in Windows Server 2008 R2 to provide a high-availability solution for virtual machines running on Hyper-V hosts. Later in Windows Server 2012, it enhanced the feature by supporting live migration in a non-clustered environment and allowing multiple live migrations simultaneously.

Windows Server 2012 R2 Preview Hyper-V live migration has been updated to support cross-version live migration. This cross-version live migration allows you to upgrade your private cloud solution from Windows Server 2012 to Windows Server 2012 R2 with zero downtime for the workloads running on your virtual machines.

Moving a virtual machine to a down-level server running Hyper-V is not supported.

Cross-version live migration can be performed using any of the live migration options supported by Windows Server 2012 including:

  • Live migration on a failover cluster
  • Live migration between failover clusters
  • Live migration using a Scale-Out File Server that supports SMB 3.0
  • Shared nothing live migration where no shared storage is used for the virtual machines

Shared Virtual Hard Disk

Hyper-V in Windows Server 2012 R2 Preview enables clustering virtual machines by using shared virtual hard disk (VHDX) files. The shared virtual hard disks enable multiple virtual machines to access the same virtual hard disk (VHDX) file, which provides shared storage for use by Windows Failover Clustering. The shared virtual hard disk files can be hosted on Cluster Shared Volumes (CSV) or on Server Message Block (SMB)-based Scale-Out File Server file shares.

Shared VHD1

The shared virtual hard disk (VHDX) is very useful, particularly in hosting environments where it enables the hosters to keep their customers’ virtual machines and their own supporting infrastructure separate. It also avoids directly exposing the fibre channel or iSCSI LUNs to clients as in Windows Server 2012 to provide shared storage to VMs.


Storage Quality of Service

Storage QoS enables to specify the maximum and minimum I/O loads in terms of I/O operations per second (IOPS) for each virtual disk in the virtual machines. Storage QoS ensures that the storage throughput of one virtual hard disk does not impact the performance of another virtual hard disk on the same host. An alert can be configured to trigger when virtual machines are not getting enough IOPS for storage access.


This feature can be useful for configuring different service-level agreements (SLAs) for different types of storage operations within the infrastructure. For instance, a hosting service provider may use this feature to configure Bronze, Silver, and Gold SLAs for storage performance available for different classes of tenants.

At the same time, an overactive or disruptive virtual machines which is saturating the storage array in the environment can be restricted.

Generation 2 Virtual Machines

Hyper-V in Windows Server 2012 R2 Preview includes two supported virtual machine generations. The virtual machine generation determines the virtual hardware and functionality that is presented to the virtual machine. A mixture of generation1 and gereation2 virtual machines are supported on the same hyper-V host.

Generation 1   Provides the same virtual hardware to the virtual machine as in previous versions of Hyper-V.

Generation 2   (Currently supported to run only 64-bit versions of Windows 8/ Windows Server 2012 or later) provides the following new functionality on a virtual machine:

  • Secure Boot (enabled by default)
  • Boot from a SCSI virtual hard disk
  • Boot from a SCSI virtual DVD
  • PXE boot by using a standard network adapter
  • UEFI firmware support


IDE drives and legacy network adapter support has been removed in Generation 2 virtual machines.

A Generation 2 virtual machine can be created using the New Virtual Machine wizard. Once a virtual machine has been created, you cannot change its generation.

Tiered Storage Spaces

Windows Server 2012 R2 preview version of Storage Spaces now support tiered storage solution that provides greater performance and scalability. The new version supports a mix of SSD and HDD in a single storage space which automatically moves the workload’s most frequently accessed data (hot blocks) to the SSD tier while rest of the workload’s data is stored on the HDD tier.

This seamless movement of data between tiers is configured by default to happen daily in 1 MB chunks, but the configuration schedule can be modified using Windows PowerShell commands.

Storage Space

Storage Spaces in Windows Server 2012 R2 can thus ensure that the workload’s hot data is always stored on the SSD tier to take advantage of the high performance of this tier, it’s cold data on the HDD tier to make use of the high capacity of this tier. Whenever a portion of the data for a particular file becomes hotter, then it gets moved from the HDD tier to the SSD tier. At the same time whenever the portion of data becomes cooler, then it gets moved from the SSD tier to the HDD tier.

Hyper-V Replica

Hyper-V Replica provides asynchronous replication of virtual machines between two Hyper-V hosts which do not have a shared storage or any particular storage hardware. Any server workload virtualized on Hyper-V can be replicated using this capability, and replication is encrypted during transmission and works over any IP-based network. The hyper-V host machines do not need to be in the same domain or even domain-joined at all, they can either be physically collocated or widely separated geographically.

Extended Repl1

Extended Repl

The replication frequency can be controlled based on the bandwidth availability and criticality of the workloads. Windows 2012 R2 provides choice of 30 seconds, five minutes, and 15 minutes.


The extended replication feature provides the ability to have a Hyper-V Replica virtual machine replicated to another Hyper-V server for extended disaster recovery capabilities. For example, virtual machine replicated from a server in the production environment to disaster recovery environment can now have the replica further replicated to another environment.

Automatic Virtual Machine Activation

This enables activation of virtual machines running on Windows Server 2012 R2 without individual activation of workloads even in a disconnected environment. AVMA binds the virtual machine activation to the licensed virtualization server and activates the virtual machine when it starts. The operating system on the guest virtual machine must be Windows Server 2012 R2 Preview Datacenter, Windows Server 2012 R2 Preview Standard, or Windows Server 2012 R2 Preview Essentials.  AVMA also provides real-time reporting on usage, and historical data on the license state of the virtual machine.

Work Folders

Work Folders address the bring-your-own device (BYOD) scenario, enabling users to store and access work files on personal PCs and devices as well as corporate PCs. Users will have a convenient location to store work files and access them from anywhere while organizations maintain control over corporate data by specifying user device policies such as encryption and lock screen passwords.


In short, the work Folders bring the functionality of Dropbox to corporate servers.


About Jayachandran PK
My passion is for Microsoft technologies and how if properly implemented, they can provide actual value for an organization especially in the field of infrastructure, virtualization and system monitoring. I work for the biggest Microsoft partner in Kuwait, specialized in project consultation and implementation services for enterprise clients. When I'm not at work, I try to contribute back through a charitable organization dedicated to prompting cultural values of Kerala. In my free time, I dabble in gardening and am also an avid solar power aficionado.

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