Hyper-V, a key feature of Windows Server 2008, has released to manufacturing (RTM) and is available for deployment into production environments. A beta of Hyper-V was included with Windows Server 2008 and this update provides the final release.
Windows Server 2008 Hyper-V, the next-generation hypervisor-based server virtualization technology, allows you to make the best use of your server hardware investments by consolidating multiple server roles as separate virtual machines (VMs) running on a single physical machine. With Hyper-V, you can also efficiently run multiple different operating systems - Windows, Linux, and others—in parallel, on a single server, and fully leverage the power of x64 computing.
Hyper-V provides a dynamic, reliable, and scalable virtualization platform combined with a single set of integrated management tools to manage both physical and virtual resources, enabling you to create an agile and dynamic data center. Hyper-V enables:
- Server Consolidation
- Business Continuity and Disaster Recovery
- Testing and Development
- Dynamic Data Center
If you are new to Hyper-V, let's run over some of the fundamentals...
A summary of key terminology specific to VM technology:
child partition: Any partition (VM) that is created by the root partition.
device virtualization: A mechanism that lets a hardware resource be abstracted and shared among multiple consumers.
emulated device: A virtualized device that mimics an actual physical hardware device so that guests can use the typical drivers for that hardware device.
enlightenment: An optimization to a guest operating system to make it aware of VM environments and tune its behaviour for VMs.
guest: Software that is running in a partition. It can be a full-featured operating system or a small, special-purpose kernel. The hypervisor is “guest-agnostic.”
hypervisor: A layer of software that sits just above the hardware and below one or more operating systems. Its primary job is to provide isolated execution environments called partitions. Each partition has its own set of hardware resources (CPU, memory, and devices). The hypervisor is responsible for controls and arbitrates access to the underlying hardware.
logical processor: A CPU that handles one thread of execution (instruction stream). There can be one or more logical processors per core and one or more cores per processor socket. In effect, it is a “physical processor.”
passthrough disk access: A representation of an entire physical disk as a virtual disk within the guest. The data and commands are “passed through” to the physical disk (through the root partition’s native storage stack) with no intervening processing by the virtual stack.
root partition: A partition that is created first and owns all the resources that the hypervisor does not own including most devices and system memory. It hosts the virtualization stack and creates and manages the child partitions.
synthetic device: A virtualized device with no physical hardware analog so that guests might need a driver (virtualization service client) to that synthetic device. The driver can use VMBus to communicate with the virtualized device software in the root partition.
virtual machine (VM): A virtual computer that was created by software emulation and has the same characteristics as a real computer.
virtual processor: A virtual abstraction of a processor that is scheduled to run on a logical processor. A VM can have one or more virtual processors.
virtualization service client (VSC): A software module that a guest loads to consume a resource or service. For I/O devices, the virtualization service client can be a device driver that the operating system kernel loads.
virtualization service provider (VSP): A provider, exposed by the virtualization stack, that provides resources or services such as I/O to a child partition.
virtualization stack: A collection of software components in the root partition that work together to support VMs. The virtualization stack works with and sits above the hypervisor. It also provides management capabilities.
Hyper‑V Architecture
Hyper‑V features a hypervisor-based architecture shown below. The hypervisor virtualizes processors and memory and provides mechanisms for the virtualization stack in the root partition to manage child partitions (VMs) and expose services such as I/O devices to the VMs. The root partition owns and has direct access to the physical I/O devices. The virtualization stack in the root partition provides a memory manager for VMs, management APIs, and virtualized I/O devices. It also implements emulated devices such as Integrated Device Electronics (IDE) and PS/2 but supports synthetic devices for increased performance and reduced overhead.
The synthetic I/O architecture consists of VSPs in the root partition and VSCs in the child partition. Each service is exposed as a device over VMBus, which acts as an I/O bus and enables high-performance communication between VMs that use mechanisms such as shared memory. Plug and Play enumerates these devices, including VMBus, and loads the appropriate device drivers (VSCs). Services other than I/O are also exposed through this architecture.
Windows Server 2008 features enlightenments to the operating system to optimize its behaviour when it is running in VMs. The benefits include reducing the cost of memory virtualization, improving multiprocessor scalability, and decreasing the background CPU usage of the guest operating system.
Integration Services
The VM integration services include enlightened drivers for the synthetic I/O devices, which significantly reduces CPU overhead for I/O than for emulated devices. The latest version should be installed in every supported guest. The services decrease the CPU usage of the guests, from idle guests to heavily used guests, and improve the I/O throughput. This is the first step in tuning a Hyper‑V server for performance.
Enlightened Guests
The operating system kernel in Windows Vista SP1, Windows Server 2008, and later releases features enlightenments that optimize its operation for VMs. For best performance, we recommend that you use Windows Server 2008 as a guest operating system. The enlightenments decrease the CPU overhead of Windows that runs in a VM. The integration services provide additional enlightenments for I/O. Depending on the server load, it can be appropriate to host a server application in a Windows Server 2008 guest for better performance.
Downloads: 
- Windows Server 2008 Hyper-V RTM (KB950050) x64 and x86 (Hyper-V Manager console & VM Connection tool)
- Hyper-V Manager Microsoft Management Console (KB952627) snap-in for Windows Vista SP1 x86 or x64
- Hyper-V Monitor: Windows Sidebar gadget (see picture)
Additional reading:
Additional resources:
- Windows Server 2008 Hyper-V Overview from TechDays 2008: video - presentation - Edwin Yuen (Senior Program Manager Virtualisation & Virtual Machine Manager) -
- “Under the Hood” of System Center Virtual Machine Manager from TechDays 2008: video - presentation - Edwin Yuen (Senior Program Manager Virtualisation & Virtual Machine Manager) -
Additional blogs: