The Different Types of Virtualization
By Bill Johonnesson
Virtualization represents an abstraction from physical resources. All uses of virtualization
are centered around this concept.
There are three major types of virtualization:
1. Server Virtualization
This type is where most of the attention is focused right now in the world of virtualization
and is where most companies begin an implementation of this technology. That's not very shocking
in light of the fact that server sprawl has become a very large and legitimate problem in enterprises
throughout the world. Where a company is simply running out of room in which to place all of
their servers, this type of virtualization would of course get viewed with strong interest.
Because each server typically serves one function (i.e., mail server, file server, Internet
server, enterprise resource planning server, etc.), with each server using only a fraction
of its true processing power, server virtualization breaks through the "one application, one
server" barrier and facilitates the consolidation of numerous servers into one physical server.
This equates to (a) less physical servers required, and (b) 70 to 80 percent or higher utilization
of existing hardware as opposed to the previous 10 to 15 percent.
Server virtualization lets one server do the job of multiple servers by sharing the resources
of a single server across multiple environments. The software lets a company host multiple
operating systems and multiple applications locally and in remote locations, freeing users
from physical and geographical limitations.
How are the servers moved over?
Most, if not all, virtualization solutions offer a migration tool to take an existing
physical server and make a virtual hard drive image of that server to the driver stack. Then
that server will boot up and run as a virtual server. There is no need to rebuild servers or
manually reconfigure them as a virtual server.
Without a doubt, the greatest advantage of server virtualization is cost. In addition
to energy savings and lower capital expenses due to more efficient use of hardware resources,
you get high availability of resources, better management, and improved disaster-recovery processes
with a virtual infrastructure. You save on physical space, reduce power consumption and the
need for as much cooling, and are able to rapidly deploy a new application without ordering
new hardware.
There are three different methods that can be employed under the server virtualization
category but I'm not going to get into them right now because I'm trying very hard to be as
simple about this as I can possibly be. Whichever method is used, the goal of server consolidation
is the same.
2. Client (or Desktop) Virtualization
This type of virtualization technology has to do with a client (a workstation desktop
or laptop pc - an end user machine). These can be very difficult for a systems administrator
to manage. Whereas any machine in the company's data center has very strict procedures regarding
what gets loaded on them and when they get updated with new software releases, it is often
a quite different scene when it comes to the end-user machine.
Even if there are supposed to be procedures followed for the above actions on an end-user
machine, those procedures are often not followed or paid much heed. A CD or DVD slot makes it
easy for non-approved software to be installed that can create problems on that machine. Quite
aside from that, end-user machines are more susceptible to malware in numerous ways - via e-mail
viruses, unwitting spyware downloads, etc. Last but not least, most end-user machines run on
Microsoft Windows which is well known for attracting attacks from hackers and cybercriminals.
IT has to not only deal with all those problems but also attend to the normal problems
inherent in client machines: keeping approved software up-to-date, patching the OS, keeping
virus definitions current, et al.
All of these factors make an IT guy's job quite challenging. So client virtualization,
with the hope of easier client machine management and security, attracts the interest of IT.
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