Virtualization Technologies

Virtualization technology has been in the limelight long enough for everyone

to know what it's all about and the benefits it offers. Therefore, it would just

suffice to say that this technology abstracts the hardware from the software so

that the hardware appears as one large pool of resources to the users.

There are several kinds of virtualization: server, storage, application,

network, and the latest entrant--desktop virtualization. Out of these, server

virtualization is the most popular with possibly the highest number of

implementations as well.

This technology allows multiple Operating Systems with their applications to

be installed on top of a single hardware server, as against loading a single OS

and application per server.

Virtualization is one of the hottest areas of IT with both hardware and

software vendors bringing out their own solutions for it.

The case for virtualization



Let's now look at some of the benefits of different kinds of virtualization

scenarios. Server virtualization allows one to load multiple OSes and apps on a

single hardware server, reduces data center complexity since you don't need to

purchase so many servers. This in turn also allows for more efficient use of IT

resources, i.e. improves server utilization, which on an average is less than

40% in most cases.

Lesser hardware also reduces power requirements in the data center, which in

turn puts lesser stress on your cooling system, thereby reducing your

electricity bills. Apart from this it is easy to deploy, and saves time while

rolling out new applications creating their replications.

The other hot trend is desktop virtualization, and there are two variants in

this. In one case, a single desktop system can run multiple OSes in virtual



environment.

In the other case, the desktop OSes run in the data center as virtual

machines, and are remotely accessed by the users. We'll talk about the other

types of virtualization later in this article.

The greatest advantage of virtualization is that replicating and recreating

identical virtual machines is just a few minutes job. For example if a software

tester needs a machine with Windows XP, Visual Studio, and Oracle installed onto

it, then one can create such a machine in a virtual environment and provide it

to the tester.

A similar configuration can then be provided to anyone else by simply

providing a copy of the same virtual hard disk that was created before. In such

a scenario the machine with the same configuration is created and installed.

Virtualization Technologies



Virtualization technologies are available both as software and hardware. In

software, the most well known names include VMWare, Xen, and Microsoft, while

the hardware virtualization vendors include Intel, AMD, IBM, and Sun. Earlier

virtualization only used to be the simulation of hardware for guest OS in which

the guest OS had to be modified. The guest OS uses some APIs to access the

required hardware. But now things are different, with the help of new

technologies, the guest OS need not to be modified and they can access the

hardware natively. There are many virtualization software and technologies.

Intel VT



Using this technology, a single CPU physically acts as if several CPUs are

working together, so that the number of guest OSes can be hosted simultaneously

on the host machine with each virtual CPU dedicated to one guest OS.

With the new instruction set, the communication process between the hardware

and the guest OS is reduced. This further reduces the overhead expenses and

enhances the overall performance.

AMDPacifica



AMD introduced its virtualization in its 64-bit CPUs, and referred it as

'Pacifica'. The company also introduced a new specification called IOMMU (Input

Output Memory Management Unit), which allows each virtual machine to have it own

interrupt.

It also provides an I/O translation unit that restricts the guest OS from

using the DMA (Direct Memory Access) directly. This technique provided complete

isolation of different guest OSes. Pacifica is not directly compatible with the

Intel's VT technology, so the program developed for Intel's VT will not run on

AMD Pacifica.

Virtual Appliances



This is one of the most powerful concepts of virtualization. With this

technology, one can deploy software solution in just a couple of minutes.

It is basically a virtual hard-disk image of any virtualization software that

can be deployed on any machine, with the same virtualization layer running that

was running on the machine on which it was created. And these https://www.pcquest.com/2007/images// are

preconfigured as well. For example, if you need to deploy a mail server within

your organization, then there are preconfigured virtual https://www.pcquest.com/2007/images// available, which

you just need to download from the Internet for the respective virtual machines

and then finally run them.

This is suited for places where people don't want to invest time on

installation and configuration. There are thousands of such virtual appliances

available on the Internet catering to different needs such as setting up mail

servers, wikis, forums, UTMs, and IPPBX.

Evolving Virtualization Technologies



We'd mentioned two other virtualization technologies, called storage and

application virtualization. The former technology does to storage what server

virtualization does to servers. In this, the data is stored wherever it finds

free space rather than seeking space on a single storage device.

Application virtualization becomes beneficial where a particular application,

which is not compatible with the native OS runs such an application within a

virtualized environment created upon the native OS. It's helpful for testing

newly developed applications which mostly contain bugs or malicious codes.

Interestingly, this technology uses fewer resources than OS virtualization.

Utility Computing



Utility computing is also called on-demand computing, i.e. whenever you

require any resources you get them and when it has been used you can give it

back.

Where's it heading?



In the near future the performance of a virtualized OS or application will

be at par with the performance in the native machine.

With technologies like XEN and MS Hypervisor that are not completely

integrated with each other, one can hope for seamless integration between these

two technologies in the near future and this seamless integration may apply to

all the future products.