Server virtualization optimizes the physical resources available and facilitate management and use of the server. More in detail, here are the main advantages of virtualization:
- reduction of physical servers: the same hardware can allow the execution of multiple virtual machines with the advantage of reducing energy consumption, heat generated, risk of hardware failures, number of rack cabinets and space needed to house all the servers
- server consolidation: it is estimated that, on average, a modern server is used only by 15 %to 20% of its maximum power. It is therefore reasonable that it can house 3 or 4 virtual machines without any performance problem
- hardware independence: the software, and in particular the operating system, is closely tied to the underlying hardware. So, if for some reason, a server installation must be moved or copied on another machine, you will may need to take into account some hardware compatibility problems. Since virtualization create layers of abstraction in an operating system, there are no problem due to physical hardware.
- stronger adaptability: virtual server can easily change based on a company’s priorities and needs. Virtualization allows to allocate the virtual hardware resources in a much faster and more flexible way
On the other hand virtualization is not problem-free. Here are main troubles:
- overhead: each virtualization decrease the overall performance of the physical server, such as time of disk access, memory access and so on. Some critical applications may be affected by the environment of the overhead introduced by virtualization;
- not all the hardware may be virtualizzabile, depending on the product used. Most trouble can be found on serial and parallel ports, USB devices, Bluetooth interfaces, graphics hardware acceleration and so on .