The Hyper-V Role in Windows Server 2008 R2
This section of our guide on installing and managing Hyper-V in Windows Server 2008 explains the Hyper-V role in...
Windows Server 2008, hardware requirements for Hyper-V and helps you get started with Hyper-V installation.
You've probably spent some time researching what's new in Microsoft's newest server operating system. This new release includes several new features that enhance Windows Server 2008 R2's security and configuration, such as DirectAccess, BranchCache, BitLocker improvements, among others.
Of all these Windows Server 2008 R2 features, those for the Hyper-V role go far in bringing enterprise-worthiness to Microsoft's virtualization platform. But before digging too deep into the features that improve Hyper-V's high-availability, let's take a step back and consider some of the product's fundamentals.
If you've gone through the process of installing Windows Server 2008 R2, you already know that the Hyper-V installation is a post-installation activity. Unlike other virtualization solutions that install an operating system and a virtualization platform simultaneously, Hyper-V is an optional "role" that is added to an existing OS instance. (For more on how Windows Server 2008 roles provide compartmentalized functionality and aid in server provisioning, check out this summary.)
To install the Hyper-V role, start within the Server Manager console. This console loads by default for administrators as they log into the server console. It can also be launched from the command line with the command ServerManager.msc. Once launched, your first step is to install the Hyper-V role. Do so by right-clicking Roles in the left pane and selecting Add Roles. In the resulting wizard, click through to the screen titled Select Server Roles. Then check the box to install the Hyper-V role and click Next.
In the following screen, titled Create Virtual Networks, you'll be asked to select one or more network adapters for virtual machines. This selection attaches the network adapter to a virtual network switch, which is a software-based switch for connecting the virtual network adapters in your VMs to your physical network. Click Next followed by Install to install the role. The installation may require one or more reboots to complete.
Note that there are certain hardware prerequisites for Hyper-V to function correctly. First, Hyper-V can be installed only on 64-bit versions of the Windows OS. This requirement was an important consideration with Windows Server 2008 release to manufacturing version and was released in 32- and 64-bit versions. Today's Windows Server 2008 R2 reduces this consideration somewhat because the OS is available only in a 64-bit version.
The second and third hardware prerequisites of Hyper-V are the support of the Data Execution Prevention security feature as well as processor-based virtualization extensions. These virtualization extensions for Intel processors are commonly referred to as VT or EPT. For AMD processors, they can be AMD-V, AMD-NPT or AMD-RVI. Consult your server's documentation prior to installing the Hyper-V role to verify that your hardware will support Hyper-V's requirements.
Installing Hyper-V R2 and Hyper-V Server R2
Every Hyper-V installation requires a hard look at available hardware resources. You'll find that maintaining virtual machine performance is a constant task in a virtual environment. To that end, multiple solutions exist for creating Hyper-V hosts from Windows Server machines.
Windows Server 2008 R2 can be installed in one of two very different ways. Its "full" version installs the entire user interface as well as all the necessary code to run common Windows applications. R2's Server Core version differs in that it installs only a bare minimum installation of the operating system. That minimum installation relies on a command shell rather than a fully-featured graphical user interface for its configuration and management activities.
Organizations can benefit from this dramatically smaller instance for many reasons: Smaller means less code, which means more security. Smaller also means that the OS uses fewer resources, leaving more resources for installed applications. This slimmed-down operating mode fits perfectly with Hyper-V's often heavy resource needs.
The Hyper-V role can be installed to either the "core" or the "full" version of Windows Server 2008 R2, with each installation being somewhat different in the steps that are required. Installing Hyper-V to a "core" instance of Windows Server 2008 R2 requires some skill with the command prompt. But, once installed, implementing and managing Windows Server 2008 Hyper-V becomes easy. If you want to squeeze as many Hyper-V VMs out of your existing hardware, here's a set of Hyper-V tips for "core" that'll help you get started:
- Install an instance of Windows Server Core to available hardware. Note the use of the command prompt to complete the installation and initial configuration of the OS.
- Windows Server 2008 R2 now includes a command-line Server Configuration tool that will assist with this initial configuration. Launch it with the SConfig.cmd command. Once launched, common configuration activities such as configuring networking, naming, adding the computer to a domain, and setting Windows Update settings can be accomplished through its textual menu.
- Once the initial configuration of the server is complete, install the Hyper-V role using the command dism /online /enable-feature / featurename:Microsoft-Hyper-V.
- This installation installs Hyper-V's server components. Managing that installation is done with the graphical Hyper-V management tools on your desktop. Those tools are a part of the Windows Vista and Windows 7 Remote Server Administration Tools, which can be downloaded from Microsoft's website.
This use of Windows Server Core as the foundation for Hyper-V is useful for licensing reasons as well. Among the new Hyper-V R2 features, Microsoft has enhanced the completely-separate-but-similarly-named product called Hyper-V Server. Hyper-V Server arrives as a preconfigured installation of Windows Server Core that is limited to running just the Hyper-V role. This special edition of Hyper-V is important because Microsoft makes it available as a free download with no requirements for licensing. This means that using it costs you absolutely nothing.
With its R2 version, Microsoft has also changed the capabilities available in Hyper-V server. This new version now includes full support for Windows Failover Clustering, as well as all the other major features available in the "regular" version of Hyper-V atop Windows Server 2008 R2 Enterprise Edition including the all-important Live Migration feature.
Greg Shields is an independent author, instructor, Microsoft MVP and IT consultant based in Denver. He is a co-founder of Concentrated Technology LLC and has nearly 15 years of experience in IT architecture and enterprise administration. Shields specializes in Microsoft administration, systems management and monitoring, and virtualization. He is the author of several books, including Windows Server 2008: What's New/What's Changed, available from Sapien Press.