What is virtualization?


The essence of virtualization is the operation of multiple separate servers on a single physical hardware. This brings significant savings in acquisition and operating costs, improves administration, speeds up the creation and deployment of a new server, and other benefits.

In this article we will talk about the so-called full virtualization that we use in our country. In other companies, you may encounter other types of virtualization (e.g. paravirtualization).

Virtualization allows a single physical server (on a single piece of hardware) to run multiple separate servers with their own operating system. The physical server emulates virtual hardware (processor, memory, disk, network card, drives, peripherals, and more) for each such virtual server. However, the fact that the server is virtualized is not visible to the customer at first glance. He has his own server with processors, memory and other components, he runs some operating system of his choice on it, he has full access to it and works with it as if this operating system was running on his own hardware.

What is virtualization good for?

Of course, it’s all about money – virtualization brings huge financial savings compared to a traditional solution. This applies to both acquisition and operating costs. The goal is to have multiple virtual servers sharing physical resources together.

Imagine that you need to run several servers in your company – a file server, a mail server, a WWW server and an accounting server. For security reasons, you don’t want all these services running on one operating system, so one possible solution is to purchase 4 physical servers. Each such physical server has its own enclosure, processors, memory, network card, hard drives and other components.

But it is obvious that these 4 servers are far from using the power of the hardware. It is a known fact that the averageCPU load on an average server is 15%. The remaining 85% is therefore unused. But even so, the processor consumes several tens of watts just by existing and being on, regardless of whether its power is used or not.

Similarly with power supplies, server motherboard, etc. These devices also consume several tens of watts just for their basic operation. Even if the server doesn’t do anything at all, its power consumption is unlikely to drop below 90 W. And that’s 90 W wasted – they will cost you about 270 CZK per month, so 3240 CZK per year on one server. And of course, you probably had to spend hundreds of thousands to acquire 4 physical servers.

The solution is therefore virtualization. You can get, for example. only 1 server for a quarter of the price and you can run virtualization on it and you will have 4 virtual servers. They will share the power of the processors and also “split” the cost of running the hardware itself. There is also a clear saving in the space where the servers are placed.

New virtual servers are also easy to set up. There is no need to plug in any new hardware, it’s often a click away in an app. Thus, the entire operation can be fully automated, saving time and manpower.

Virtualization with us

As part of our services, we offer the operation of virtual servers on our physical servers. We run several dozens of them on one server, the resulting power consumption per virtual server is about 4 W. That’s a crucial difference, don’t you think? Thanks to this we can offer it so cheaply – from 100 CZK per month (without VAT).

Processor power is shared – each VPS has one or more virtual processors that collectively take turns to time on the physical processors. For more see. VPS – explanation of virtual processors. We don’t offer dedicated CPU power, the whole virtualization would be pointless and we would be wasting unused server power. Then our VPS services would also have to be priced differently. If the customer insists on non-shared power, he can choose Dedicated servers where they have the entire physical machine to themselves.

Memory is reserved – as much RAM as the customer orders, they will have for themselves. Memory sharing is problematic. In addition, the advantage of non-shared memory is that the operating system running on the virtual server will use the unused memory for caching, thus reducing the load on the hard disks. See the discussion of file system caching for more information.

For full virtualization, we use a KVM (Kernel-Base Virtual Machine) product running on top of the Linux operating system. See www.linux-kvm.org. As alternatives there are e.g. VMWare, Microsoft Hyper-V and Oracle VirtualBox products.

Be careful not to confuse the KVM (Kernel-Base Virtual Machine) abbreviation mentioned here with the other KVM (Keyboard, Video, Mouse) abbreviation mentioned in the next section.

It is possible to run any operating system on the virtual server – e.g. Linux or Windows. Either we pre-install the operating system according to the customer’s request during the setup or the customer can install the OS himself by connecting the installation CD/DVD (see below).

Access to the virtual server device

The virtual server has, among other things, a virtual screen, keyboard, mouse and CD/DVD drive. But since these are virtual things, how do you get to them and how do you use them? Of course, using the appropriate programs.

KVM (or Keyboard, Video, Mouse) is a technology that allows access to the monitor, keyboard and mouse of a remote computer. Simply install the necessary program on your home computer, connect remotely to the virtual server, and the contents of the virtual server monitor will be displayed on your computer monitor, and you can use your mouse and keyboard to control it as if you were sitting right at the server. A protocol called VNC is used for this purpose. For more see. VPS – access to the server via VNC.

Of course, customers also need to be able to attach a CD/DVD to their virtual server from which they want to install an application (or even the operating system itself). This is also possible and is done via the customer administration, where the customer selects the desired CD/DVD from the list and clicks to connect it to the server. Again, this is solved by software, our technicians do not run anywhere with the CD and do not insert it into any drive, because the drive does not even physically exist. For more see. VPS – CD/DVD connection.

All of the above is done from the comfort of the customer’s home (or office) – no need to go anywhere or do anything.