Virtualization lets you operate several operating systems at once (Windows, Linux, Mac OS, etc.) on the same physical machine. The idea is to think about several virtual machines (Windows 7, or a Windows 2012 server, for instance) on the same physical machine, where the virtual machines then share the material resources of the physical server.
Instead of having multiple physical machines with only one operating system installed on each one, one physical machine is used to virtualize several operating systems. In particular, virtualization was created to deal with the issue of underutilizing hardware resources.
History of virtualization
In the 1970s: A large portion of the work done on virtualization took place at the IBM science center in Cambridge, in collaboration with MIT, where the experimental CP/CMS system was developed, then becoming the VM/CMS product (then called “Hypervisor”). Next, mainframes (IBM servers) were capable of virtualizing their operating systems with specific, proprietary technologies, both software and hardware. In 1979, for instance, an optional, micro-coded VM accelerator was announced on IBM 4331 and 4341 machines.
The 1980-1990s: In the second half of the 1980s and early 1990s, prototype virtualization was created for personal computers. These solutions could either be purely software, or coupled with additional equipment (adding a processor, network card, etc.). On Amiga computers that were equipped with differing processors, like the 80386 and 80486, 68xxx and the PPC, it was possible to launch other OS, such as Windows, Mac OS, or even Linux solutions, all as multitasks running on Amiga OS. For PCs, there were emulators such as SideCar and PC Task, and on Macintosh, there was Emplant and Shapeshifter.
Late 1990s and early 2000s: In the second half of the 1990s, emulators on x86 systems running on old machines from the 1980s were very popular, especially Atari, Amiga, Amstrad computers and NES, SNES, Neo-Geo AES consoles. In the late 1990s and early 2000s, the company VMware developed and popularized a proprietary system of software virtualization of x86-type architectures. The freeware Xen, KVM, QEMU, Bochs, Linux-VServer, Virtual Box and proprietary yet freeware VirtualPC, Virtual Serve and VMware Server achieved popularity in virtualizing in the world of x86.
Virtualization addresses many needs:
- Making your infrastructure and resources profitable through smarter utilization
- Executing several types of operating systems (Linux, Mac OS, Windows)
- Reducing hardware running costs (in electricity, server leasing, cooling, etc.)
- Centralized logical/physical administration
- Rapid deployment
- Flexibility in hardware development
- Resource allocation and load balancing
- Partitioning and security.