explain in your own words the concept of virtualisation? How does it work and what software solutions exist?

Question

also why so system adminstrators often aim to virtualise services today?

Answer 1

Virtualization is about sharing of physical resources.

When computers were less powerful in older days, they could not perform multiple functions. All the resources of the computer is required to perform a single task. Compared with today's computers, they were lumbering dinosaurs.

Nowadays, computers can perform several tasks at the same time. Multiple processes run in the background. And with technological innovation and advancements in manufacturing, costs are also droppping.

Costs of components are not linear. The price of a 80 GB hard drive is not twice that of 40 GB. Purchasing 2 40 GB hard drives costs more than a 80 or 120 GB hard drive. It is the same with CPUs and memory modules.

Using virtualization, a 120 GB hard drive could shared by 2 separate computers. However, this is different from logical partitioning. Other components, such as the CPU and memory could be virtualized as well.

Using virtualization, a physical PC with a single CPU could be 'made' into 2 PCs with their own separate processing, memory and storage capacities. It is as if there are 2 PCs even though physcially there is actually only 1.

For example, a PC with a P4 CPU, 1 GB RAM and 120 GB hard drive could be virtualized into a PC using 60% of CPU processing, 512 MB memory and 80 GB hard drive, and another PC using 40% of CPU processing, 512 MB memory and 40 GB hard drive. A 3rd PC could even be virtualized if want to -- just reduce the capabilities of the other 2.

Virtualization is used extensively for servers because rack space is expensive. With virtualization, the physical footprint is reduced significantly while retaining all the functionalities that are needed.

No longer system administrators need to run around to manage multiple servers. Multiple servers have been virtualized from a single powerful server. They only need to switch from one virtual server to another, all at the same spot.

Virtual PC and VMWare are 2 of the more popular virtualization software available today. There are also open-source virtualization software, such as Xen.

Answer 2

Think of it as one step further than emulation of a computer, it is a computer-in-computer at full speed; I'm not sure which software is a "virtualizing" solution.