There is a trend today in IT to move back from a distributed environment to a consolidated environment. Indeed, the consolidated environment, conceptually, looks very similar to the mainframes of old. Back then IT workers connected to the mainframe via a keyboard, and text was sent back to a dumb terminal whose sole function was to display the text on the screen and send keyboard instructions to the mainframe. All applications ran on the mainframe. What the user saw on the dumb terminal was configured by configuration settings stored on the mainframe. Essentially, the mainframe hosted the applications and desktops. The mainframe was the server.
With the advent of the PC, this all changed. The PC ran the desktop and ran applications either locally on the PC or remotely on a server. This caused many problems and proved to be expensive. The problems were:
- Management: Consider a desktop upgrade -- each machine has to be visited by IT personnel either in person or remotely to do the upgrade. While remote software distribution tools allow for remote upgrades, they are never simple operations to carry out.
- Inefficient use of resources: In any enterprise, most servers spend large amounts of time idling.
- Business continuity: Should an event, like a power failure or a flood, make a data center inaccessible, it's difficult to resume essential business functions in another location.
- Remote access: Increasing numbers of users are mobile. While notebooks allow users to work from home or other locations, being able to access a desktop from a kiosk in an airport, for example, is extremely valuable.
Desktop virtualization and server virtualization solves these problems by unifying applications, servers and desktops. Similar to the mainframe, applications are hosted on virtual servers running in a hosted environment.
There are some drawbacks to virtualization. First, virtualization makes sense typically in larger environments where IT can afford the powerful servers needed to support a virtualized environment. The second problem is one of continuity: should the server hosting the virtualized environment go down, it will affect a very large number of users. Businesses deploying virtualized solutions have to think through these problems.
This was first published in March 2008