Virtualization: Understanding the Hyper-V Hypervisor

By Doug Lowe

Hyper-V is a built-in component of all modern versions of Windows. So, to use Hyper-V, you don’t need to purchase any additional software from Microsoft. If you own a modern Microsoft operating system, you already own Hyper-V.

Don’t be confused by the fact that Hyper-V is an integral part of Windows: Although Hyper-V is built into Windows, Hyper-V is not a Type-2 hypervisor that runs as an application within Windows. Instead, Hyper-V is a true Type-1 hypervisor that runs directly on the host computer hardware. This is true even for the Client Hyper-V versions that are included with desktop versions of Windows.

In Hyper-V, each virtual machine runs within an isolated space called a partition. Each partition has access to its own processor, RAM, disk, network, and other virtual resources.

There are two types of partitions in Hyper-V: a parent partition and one or more child partitions. The parent partition is a special partition that hosts the Windows operating system that Hyper-V is associated with. Child partitions host additional virtual machines that you create as needed.

When you activate the Hyper-V feature, the hypervisor is installed and the existing Windows operating system is moved into a virtual machine that runs in the parent partition. Then, whenever you start the host computer, the hypervisor is loaded, the parent partition is created, and Windows is started in a virtual machine within the parent partition.

Although it may appear that the hypervisor is running within Windows, actually the reverse is true: Windows is running within the hypervisor.

In addition to the Windows operating system, the parent partition runs software that enables the management of virtual machines on the hypervisor. This includes creating new virtual machines, starting and stopping virtual machines, changing the resources allocated to existing virtual machines (for example, adding more processors, RAM, or disk storage), and moving virtual machines from one host to another.