Virtual Computers


In my next edition of “Geeks Today” I’d like to tell you something about virtualization. But before I can do so I need to give you a little bit of background information.

If you navigate to a website or use a certain application at your job or if you connect/send data to a database (by using a website, interface, whatever), you will be working with a server.
A server is like, a very big and powerful computer. But I mean really powerful, these server are build to be online non stop and to support hundreds of people to connect to them at the same time.

These servers run the applications where you, as end user, will eventually connect to. The best example, again, is a website. Let’s take a commercial website for example.
You want to buy certain goods, so what happens is you connect to the server by navigating to the website.
The webpages are available on the server.

Next you will need to enter your information about what you like to order, how many you’d like to order, your name, address, etc…
The website you are currently on is connected to a database and the moment you hit the SEND button on the website, all the data you’ve just entered will be send to the database. This database is/can be running on a different server.

As I said, these are rather large computer with a huge capacity. This also brings problems with them.
They are for example very noisy, this is because they also generate a lot of heat (lot of power, lot of heat). All this heat needs to be controlled and so there are a lot of coolers in the server. These coolers make a lot, and really, A LOT of noise.

Therefore servers are always placed in a server room. This room is (well normally at least) fireproof, waterproof, secured and air cooled. Indeed! There is air conditioning in this room. The coolers of the server will not always do, certainly when they are in a room with no ventilation (which is most likely the case since a server room is, as just mentioned secured). So they need to be air cooled.

As you came to notice, it is a bit of a pickle to run a server. You pay a certain price for the incredible performance. Specially when you have a lot of different server applications which need to run on dedicated (so different) servers.

It costs a lot to buy, install and maintain all of these servers. But a few years a ago a new concept was introduced. Virtual computing!
You have one powerful host server which allows you to run multiple smaller servers. I’ll give you a practical example.

A host server runs an operating system which allows virtualization. One of the most famous ones is ESX. The administrator of the machine connects with a client tool to the ESX host machine and start to define other servers.
Suppose the host machine has 16GB of ram memory, 1TB of HDD and 4 quad core CPU’s.
If we want to run our website and store our data somewhere we need 2 servers.
And that is what we requested to the administrator :’).
This administrator creates 2 virtual machines. The webserver get’s 4 (of the 16) GB of ram memory, 200GB (of the 1TB) HDD and 2 (of the 4) quad core CPU’s.
The database get’s 12GB of ram, 800GB of HDD and the 2 other CPU’s.

The webserver will be installed with Windows and the database will be installed with linux. Both servers will be know as 2 separate machines yet they run on one and the same (!!) host machine.

I found a small screenshot of the esx console with 2 servers defined. And I will exploit it right now!


The window in the back is the ESX console and in the left hand column you see OpenSUSE 11.1 and Win2003.
The screens in front show the interface of windows 2003 (which is a server edition, don’t be alarmed if you haven’t heard of this) and the terminal interface of OpenSuse 11.1.

The right hand screen also shows some information about how much resources the server has (Harddisk, cpu usage etc).

Like this you will need a lot less servers, a lot less maintenance and a lot less aircos ;-)…

Oh by the way, one more thing. I just needed to show you this! I googled on “virtual computer” and checked the images. This is one of the pictures I came across (one of the first hits the be exact).


Who said technology couldn’t be fun?

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