What is Virtualisation?
Current computer hardware was originally designed to run a single operating system and a single application, but the advent of virtualisation has made it possible to run multiple operating systems and multiple applications on the same computer at the same time, increasing the utilisation and flexibility of the hardware.
Virtualization is a technology that can benefit anyone who uses a computer, from IT Professionals and Mac enthusiasts to commercial businesses and government organizations. Virtualisation allows an organisation to save time, money and energy whilst achieving more with the computer hardware they currently own.
How Does Virtualisation Work?
Essentially, virtualisation allows you to consolidate hardware platforms into software appliances. Software such as VMware ESX, Citrix XenServer and Microsoft Hyper-V, transform or “virtualise” the hardware resources of an x86-based computer—including the CPU, RAM, hard disk and network controller—to create a fully functional virtual machine that can run its own operating system and applications.
Virtualisation starts with the installation of a thin layer of software directly on the computer hardware, or as an application on a host operating system. This software layer creates virtual machines and contains a virtual machine monitor or “hypervisor” that allocates hardware resources dynamically and transparently so that multiple virtual machines share hardware resources without interfering with each other, making it possible to safely run several operating systems and applications at the same time on a single physical host.
What is a Virtual Host?
A virtual host is a physical hardware device, i.e. an x86-based server which is configured in such a way as to enable it to house multiple virtual guests (Virtual Machines/Appliances). There are 2 common ways in which the physical host can be utilised as a virtual one: firstly by installing an operating system such as Windows 2008 + a virtualisation application such as VMWare Server or Microsoft Hyper-V. The alternative is to install a Hypervisor Platform such as VMWare ESX or Citrix Xenserver directly onto the Host - enabling more resources to be utilised by the virtual layer. The server is now capable of hosting multiple Virtual Machines or Virtual Appliances.
What is a Virtual Machine?
A virtual machine is an isolated software container that runs its own operating system and applications as if it were a physical computer. A virtual machine contains its own virtual (ie, software-based) CPU, RAM hard disk and network interface card.An operating system is not able to distinguish between a virtual machine and a physical machine, nor can applications or other computers on a network. The virtual machine sees itself as a “real” computer. But, a virtual machine is composed entirely of software and contains no hardware components.
What is a Virtual Appliance?
A virtual appliance is a pre-built software solution that has been configured for a specific purpose, comprising of one or more Virtual Machines that are packaged, updated, maintained and managed as a unit. These are often built utilising Open Source OS`s such as Linux, making them compact and secure. Commonly just one application will be installed which has a specific function: WAN acceleration, performance monitoring, security management for example. Unlike a physical hardware appliance, these software appliances allow customers to easily acquire, deploy and manage a complete solution.
