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Server Virtualization Explained
Put simply, server virtualization allows you to run multiple independent virtual operating
systems on a single physical computer, which in turn allows you to squeeze the most
utilization out of your servers.
For example, you know that 1U dual-socket, dual-core server in your datacenter that
you think is near its end of life? By virtualizing it, you can turn it into ten (possibly even
more) virtual servers running ten (possibly even more) virtual operating systems.
Although virtualization does not increase computing power (it actually decreases it
because of the overhead involved in virtualization), it does increase server efficiency and
utilization overall. Plus, because a reasonably powerful server these days is much less
expensive than a top-of-the-line model was a few years ago, you can buy a new server and
cost-effectively virtualize your existing machines onto it.
And, obviously, this results in less money being spent for hardware and less money
being spent for power and cooling.

Advantages
The ecological advantages to consolidation are clear, and we’ve been eager to remind you
about them in preceding chapters. However, not only will you save on electricity costs to
operate and maintain the equipment, you will also save money outright with equipment costs.
Remote Users
By virtualizing terminal servers—that is, servers that present a remote desktop to your
users—an organization can allow users to work remotely. Consider the organization
depicted in Figure 12-1.
As Figure 12-1 shows, server virtualization allows workers to access the content of the
server across a WAN link.
The application need not be installed on the employee’s computer, and the application
need not be installed on every desktop in your organization. Only those users who need to
have access to their specific desktop environment can use it.
You can also provide a secure and standard corporate enterprise environment across
your organization’s desktops—whether they’re in Beijing, Bali, or Branson, Missouri.
Fast Provisioning
Provisioning new infrastructure is less time consuming than it used to be. Virtual servers
combine easy-to-use deployment software with preconfigured devices. This allows you to
introduce new services and applications faster and easier than if they were rolled out
conventionally.

Rehosting
There’s likely some legacy software humming away on an old server (or two) somewhere in
your datacenter. And more than likely, you haven’t been eager to move that application to a
new server in fear that it won’t work. Further, chances are even better that this dinosaur of
a physical server is inefficient, generates a lot of heat, and sucks up a lot of power.
Through virtualization, you can move those legacy applications to a new server, and
you won’t have to pay huge electrical bills. You’ll still have that charming old application.
And best of all, you can sleep at night, not worrying if the old server has finally died.