There have been lots of new stories and article about Hyper-V and virtualization coming to Windows 8 and it suddenly occured to me that not everyone may be familiar with these advanced concepts.
Let’s step back a bit and talk about virtualization. Wikipedia is the source for most of this info.
Virtualization, simply put, is the creation of a virtual (rather than actual) version of something, such as a hardware platform, operating system, a storage device or network resources.
Hardware virtualization or platform virtualization refers to the creation of a virtual machine that acts like a real computer with an operating system. Software executed on these virtual machines is separated from the underlying hardware resources. For example, a computer that is running Microsoft Windows may host a virtual machine that looks like a computer with Ubuntu Linux operating system. Subsequently, Ubuntu-based software can be run on that virtual machine.
Desktop virtualization is the concept of separating the logical desktop from the physical machine. One form of desktop virtualization, virtual desktop infrastructure (VDI), can be thought as a more advanced form of hardware virtualization: Instead of directly interacting with a host computer via a keyboard, mouse and monitor connected to it, the user interacts with the host computer over a network connection (such as a LAN, Wireless LAN or even the Internet) using another desktop computer or a mobile device.
Now the hypervisor plays a pretty central role in virtualization.
A hypervisor, also called a virtual machine manager, is a program that allows multiple operating systems to share a single hardware host.
Each operating system appears to have the host’s processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual mahines) cannot disrupt each other.
Basically the hypervisor is a traffic cop that allocates VM resources and makes sure they all run smoothly and independent of each other.
There are two general types of hypervisor:
Type 1 (or native, bare metal) hypervisors run directly on the host’s hardware to control the hardware and to manage guest operating systems. A guest operating system thus runs on another level above the hypervisor.
This model represents the classic implementation of virtual machine architectures;
Type 2 (or hosted) hypervisors run within a conventional operating system environment. With the hypervisor layer as a distinct second software level, guest operating systems run at the third level above the hardware.
In other words, Type 1 hypervisor runs directly on the hardware; a Type 2 hypervisor runs on another operating system, such as Linux.
Interest in the high-profit server-hardware market sector has led to the development of hypervisors for machines using the Intel x86 instruction set, including for traditional desktop PCs.
One of the early PC hypervisors, the commercial-software VMware, debuted in 1998. Parallels, Inc. introduced Parallels Workstation, which is primarily used on PCs, in 2005 and Parallels Desktop for Mac, which runs on Mac OS X (10.4 for Intel or higher), in 2006.
There is massive speculation that Windows 8 will be the first Microsoft client OS to really focus in a big way on virtualization at the desktop level.
Hopefully there will be more news at the BUILD conference.