Page 83 - How Cloud Computing Is Transforming Business and Why You Cant Afford to Be Left Behind

VIRTUALIZATION C HANGES EVERYTHING

old version of the application, sidestepping the need to mi-
grate it. Instead, the application runs in a virtual machine with
the old operating system. Remember that both the virtual ma-
chine and the virtual machine’s host have their own operat-
ing system. They may have started out at the same time and
with the same version, but now they part ways. The hypervisor

beneath the virtual machine is indifferent to which version of
an operating system it is talking to. It continues to direct the
hardware instruction set on what to do, just as before.
This characteristic becomes extremely useful in a cloud
data center. For one thing, a multitenant server is going to need
to process the needs of varied end users. Some may send a
workload under Windows, others under Linux, and still others

under Solaris. The hypervisor doesn’t care. It will run them all
side by side on the same physical server, giving cloud suppliers
a great deal of flexibility in choosing how they wish to manage
their resources and which environments they wish to support.
More important, the end user of the cloud now has the
means of packaging the application and the version of the op-
erating system with which it runs best as a single set of files,
something that is currently called a “virtual appliance.” The
end user in this case is usually a skilled programmer or IT man-

ager acting on behalf of business end users. What’s important
is that this set of files can be transferred over the Internet to
whatever cloud service the IT manager chooses. Unfortu-
nately, different clouds accept different file formats, but a
reasonably informed IT manager can cope with specific re-
quirements and cast the virtual appliance in the correct for-
mat. By freeing itself from dependence on an underlying

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