server capacity was poorly utilized. The idea with
virtualization is to build one large server and run more
than one application on it. Sounds simple, right? Many
of the techniques mentioned earlier, from the days of the
mainframe, were leveraged to create an environment
where the underlying server hardware could be
virtualized. The hypervisor was created to handle all of
the time slicing and hardware simulation. This made it
possible to run various applications and operating
systems at the same time and reap the benefit of better
utilization of resources. Figure 13-9 shows this concept.
Figure 13-9 Virtualized Application Stack
Virtualizing hardware had other benefits, too. The ability
to make applications portable and not tied to a single
server allows for mobility in the data center. If a server
needs to be worked on, you simply move the running
virtual machine to another server and never need to take
down the application. You can also create common
deployment packages for new virtual machines and
applications; this gives administrators the ability to
quickly provision a new server in a consistent and secure
manner.
The virtualized application is a key aspect of cloud, but
virtualization and cloud are not synonymous. A cloud
environment could easily be configured to deploy a
physical server as well as a virtual machine. Conversely,