An Introduction to Virtualization

Baby Steps Leading to World-Class Innovations

Many "little" problems have called for companies like VMware and Microsoft to develop software throughout the years. As technology progresses, several hardware types become defunct and are no longer manufactured or supported. This is true for all hardware classes, from server systems to those old yet glorious video game systems that are collecting dust in the attic. Even though a certain architecture is abandoned by its manufacturers, existing software may still be of great (or perhaps sentimental) value to its owners. For that reason alone, virtualization software is used to emulate the abandoned architecture on a completely different type of machine.

A fairly recent example for this (besides the obvious video game system emulators) is found integrated into Apple's OS X: Rosetta. Using a form of real-time binary translation, it is able to change the behavior of applications written for the PowerPC architecture to match that of an x86-app. This allows a large amount of software that would normally have to be recompiled to survive an otherwise impossible change in hardware platforms, at the cost of some of its performance.

Hardware platforms have not been the only ones to change, however, and the changes in both desktop and server operating systems might force a company to run older versions of the OS (or even a completely different one) to allow the use of software coping with compatibility issues. Likewise, developers have a need for securely isolated environments to be able to test their software, without having to compromise their own system.

The market met these demands with products like Microsoft's Virtual PC and VMware Workstation. Generally, these solutions offer no emulation of a defunct platform, but rather an isolated environment of the same architecture as the host system. However, exceptions do exist (Virtual PC for the Mac OS emulated the x86 architecture on a PowerPC CPU, allowing virtual machines to run Windows).

Putting together the results of these methods has lead to a solution for the problem quietly growing in many a company's server room. While the development of faster and more reliable hardware was kicked up a notch, a lot of the actual server software lagged behind, unable to make proper use of the enormous quantity of resources suddenly available to it. Companies were left with irreplaceable but badly aging hardware, or brand new servers that suffered from a very inefficient resource-usage.

A new question emerged: Would it be possible to consolidate multiple servers onto a single powerful hardware system? The industry's collective answer: "Yes it is, and ours is the best way to do it."