A First Look at Windows Server 2008 Hyper-V

Virtualization is one of today’s hottest IT technologies, and Windows Server 2008’s new native virtualization feature, Hyper-V, is a significant new competitor that has the potential to change the market. VMware ESX Server is the current market favorite. To make an informed decision about Hyper-V, you need to understand how the architectures of the two products compare. In addition, Hyper-V introduces some important new features, and you’ll want to see how Hyper-V and the older Virtual Server 2005 R2 relate to each other. Finally, to enrich your understanding of Hyper-V I’ll show you how to set it up and use it.

Prerequisites for Hyper-V
Unlike Microsoft’s Virtual Server 2005 R2, which runs on both 32-bit and 64-bit systems, Hyper-V requires an x64-based system that has either Intel-VT or AMD-V support. In addition, the host system’s CPU must have data execution protection enabled (the Intel XD bit or the AMD NX bit). Microsoft will provide Hyper-V virtualization technology with the following versions of the Windows Server 2008.

• Server 2008, Standard: $999 with five Client Access Licenses (CALs)
• Server 2008, Enterprise: $3,999 with 25 CALs
• Server 2008, Datacenter: $2,999 per processor

Like the Windows Server 2003 R2, Enterprise and Datacenter Editions, the Server 2008, Enterprise Edition allows up to four virtual Windows instances with no additional licensing costs, and Server 2008 Datacenter Edition allows an unlimited number of virtual Windows instances with no additional licensing costs. You can use Hyper-V with both the full Server 2008 installation, or with Server Core for any of the Server 2008 editions. In addition Microsoft will offer a standalone version called Hyper-V Server for $29.

Windows Server Hyper-V Architecture
Designed to compete with VMware’s ESX Server, Hyper-V has been built from scratch based on a new microkernel architecture. Figure 1, shows an overview of the new Server 2008 Hyper-V architecture. For a quick comparison of ESX Server and Hyper-V, see the sidebar “Feature for Feature: VMware ESX Server vs. Microsoft Hyper-V.”

Unlike Virtual Server’s hosted virtualization model, which requires installing the virtualization software on top of a host OS, Hyper-V is a virtualization layer that runs directly on the system hardware with no intervening host OS. The Hyper-V architecture consists of the bare metal microkernel hypervisor and parent and child partitions.

All Hyper-V implementations have one parent partition. This partition manages the Hyper-V installation. The Windows Server Virtualization console runs from the parent partition. In addition, the parent partition is used to run thread-supported legacy hardware emulation virtual machines (VMs). These older emulation-based VMs are essentially the same as the VMs that run under a hosted virtualization product such as Virtual Server.

Guest VMs run on Hyper-V child partitions. Hyper-V’s child partitions support two types of VM: high performance VMBus-based VMs or hosted emulation VMs. VMBus VMs include Windows Server 2003, Windows Vista, Server 2008, and Xen-enabled Linux. The new VMBus architecture is essentially a high performance in-memory pipeline that connects Virtualization Service Clients (VSCs) in the guests with the host’s Virtual Service Provider (VSP). Hosted emulation VMs support guest OSs that don’t support the new VMBus architecture. These OSs include, Windows NT, Windows 2000, and non-Xen enabled Linux, like SUSE Linux Server Enterprise 10.

Hyper-V and Virtual Server Server 2008
Hyper-V introduces capabilities that aren’t available with Virtual Server 2005 R2. Running exclusively on the x64 platform, Hyper-V supports host systems with up to 1TB of RAM, and Hyper-V doesn’t limit the number of active VMs; the only limitation comes from the capabilities of the host server hardware. In addition, the Hyper-V VMs are more scalable than Virtual Server VMs. Hyper-V supports both 32-bit and 64-bit guest OSs. Not only can guest VMs take advantage of Hyper-V’s higher performing VMBus architecture, but guest VMs also can use more RAM and CPU than Virtual Server offers. Virtual Server 2005 R2 has no support for virtual SMP and is limited to 3.6GB of RAM per VM. Hyper-V supports up to 4 virtual processors per VM and up to 32GB of RAM per VM. To take full advantage of this support, the host system must have at least 4 cores and more than 32GB of physical RAM.

Hyper-V provides new storage features. Storage Area Network (SAN) support lets you boot VMs and implement guest-to-guest failover clustering, as well as virtual server host failover clustering. Hyper-V also introduces the pass-through VM access storage feature. With Hyper-V, you can access virtual hard disk (VHD) images without mounting the VHD image in a running VM. Hyper-V can also take advantage of Volume Shadow Copy Service (VSS) for live VM backup. On the networking side, Hyper-V includes a new virtual switch with support for Windows Network Load Balancing (NLB) across VMs on separate servers. In addition, Hyper-V allows multiple snapshots of running VMs with the ability to revert back to any of the saved snapshots.

Installing Hyper-V
Hyper-V is not installed in Server 2008 by default. To install Hyper-V, you use the Server 2008 Server Manager. Click Start, Programs, Administrative Tools, and then select the Server Manager option. In Server Manager, add the virtualization role by clicking Add Roles, which displays the Add Roles Wizard shown in Figure 2.

In the Add Roles Wizard, check the Windows Server virtualization role. Then click Next and step through the wizard’s screens to learn about and configure Hyper-V. The wizard first explains that you might need to configure your BIOS for virtualization support, and it provides links to Windows Server Virtualization Online Help files. Next, the wizard prompts you for the Local Area Connections that you want to associate with your virtual networks. By default, the wizard creates one virtual network for each physical network adapter that’s installed. Next, you’re asked to confirm your selections and prompted to restart your system.

AMD-V systems have virtualization support enabled by default. In contrast, if your system uses Intel-VT virtualization, check your system’s BIOS configuration during the boot process and make sure that virtualization is enabled. For systems with Intel motherboards, press F2 during the boot process to see the BIOS configuration. You can set the Enable VT option to enable virtualization support in the processor.

After the system reboots, the Resume Configuration Wizard screen appears. Use it to finish installing the Windows Server Virtualization role. The new Windows Server Virtualization role will then be listed under Server Manager’s installed roles node.