Virtualization products can use several different architectures to share a computer’s hardware resources among VMs. The earlier type of virtualization products, including Microsoft Windows Virtual PC and Microsoft Virtual Server, requires a standard OS installed on a computer. This becomes the “host” OS. Then you install the virtualization product, which adds the hypervisor component. The hypervisor essentially runs alongside the host OS, as shown in Figure 3-1, and enables you to create as many VMs as the computer has hardware to support.

Virtualization architectures

FIGURE 3-1 A hybrid VMM sharing hardware access with a host operating system

This arrangement, in which the hypervisor runs on top of a host OS, is called Type II virtualization. By using the Type II hypervisor, you create a virtual hardware environment for each VM. You can specify how much memory to allocate to each VM, create virtual disk drives by using space on the computer’s physical drives, and provide access to peripheral devices. You then install a “guest” OS on each VM, just as if you were deploying a new computer. The host OS then shares access to the computer’s processor with the hypervisor, with each taking the clock cycles it needs and passing control of the processor back to the other.

Type II virtualization can provide adequate VM performance, particularly in classroom and laboratory environments, but it does not provide performance equivalent to separate physical computers. Therefore, it is not generally recommended for high-traffic servers in production environments.

The virtualization capability built into Windows Server 2012 R2, called Hyper-V, uses a different type of architecture. Hyper-V uses Type I virtualization, in which the hypervisor is an abstraction layer that interacts directly with the computer’s physical hardware—that is, without an intervening host OS. The term hypervisor is intended to represent the level beyond the term supervisor, in regard to the responsibility for allocating a computer’s processor clock cycles.

The hypervisor creates individual environments called partitions, each of which has its own OS installed and accesses the computer’s hardware via the hypervisor. Unlike Type II virtualization, no host OS shares processor time with the hypervisor. Instead, the hypervisor designates the first partition it creates as the parent partition and all subsequent partitions as child partitions, as shown in Figure 3-2.

Virtualization architectures

FIGURE 3-2 A Type I VMM, with the hypervisor running directly on the hardware

The parent partition accesses the system hardware through the hypervisor, just as the child partitions do. The only difference is that the parent runs the virtualization stack, which creates and manages the child partitions. The parent partition is also responsible for the subsystems that directly affect the performance of the computer’s physical hardware, such as Plug and Play, power management, and error handling. These subsystems also run in the OSs on the child partitions, but they address only virtual hardware, whereas the parent, or root, partition handles the actual hardware.


It might not seem like the Hyper-V role in Windows Server 2012 R2 provides Type I virtualization,
because it requires the Windows Server OS to be installed and running. However, adding the Hyper-V role actually converts the installed instance of Windows Server 2012 R2 into the parent partition and causes the system to load the hypervisor before the OS.


This article is a part of 70-410 Installing and Configuring Windows Server 2012 Prep course, more articles in this course are :

Connecting to storage area network (SAN)

At its most basic level, a storage area network (SAN) is simply a network dedicated to highspeed connections between servers ...
Read More

Creating virtual switches

A virtual switch, like its physical counterpart, is a device that functions at Layer 2 of the Open Systems Interconnect ...
Read More

Creating virtual network adapters

Once you have created virtual switches in Hyper-V Manager, you can connect VMs to them by creating and configuring virtual ...
Read More

Configuring NIC teaming in virtual network environment

As explained earlier in, “Configuring Servers,” NIC teaming is a Windows feature that enables administrators to join multiple network adapters ...
Read More

Creating virtual network configurations

Hyper-V makes it possible to extend nearly any existing physical network configuration into its virtual space or create a completely ...
Read More

IPv4 addressing

As you probably know, The IPv4 address space consists of 32-bit addresses, notated as four 8-bit decimal values from 0 ...
Read More

IPv6 addressing

As most administrators know, IPv6 is designed to increase the size of the IP address space, thus providing addresses for ...
Read More

Subnetting IPv6 Addresses

As with IPv4, administrators can create a hierarchy of subnets using IPv6 addresses. However, in IPv6, no subnet masks are ...
Read More

Planning an IP transition

Many enterprise administrators are so comfortable working with IPv4 addresses that they are hesitant to change. Network Address Translation (NAT) ...
Read More

Understanding DHCP

DHCP is a service that automatically configures the IP address and other TCP/IP settings on network computers by assigning addresses ...
Read More

70-410 Installing and Configuring Windows Server 2012 Prep course includes following practice tests:

No posts found.