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Get inside Virtualisation

by Ken Hess

There are many alternatives to VMware’s expensive and proprietary software. Join us as we investigate four of the most prolific tools kickstarting the revolution in open source virtualisation…

LUD85_Cover_SLIMThis article originally appeared in issue 86 of Linux User & Developer.
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There are many alternatives to VMware’s expensive and proprietary software. Join us as we investigate four of the most prolific tools kickstarting the revolution in open source virtualisation…

Let’s start with a brief overview: Virtualisation leverages computing hardware by allowing you to run multiple computer workloads on a single system. Computer workloads take various forms: from shared instances of the same operating system to fully virtualised computers running as if they were standalone physical systems. Using virtualised infrastructure saves money by decreasing the amount of rack space used by physical hardware,
reducing power consumption and heat generated, and decreasing your
overall hardware budget.

The most popular software for desktop and server virtualisation is VMware. Its array of solutions is the industry standard. However, it’s expensive – so much so that it’s prohibitive for some small and medium-sized businesses to adopt. In a reaction to commercial virtualisation’s high entry costs, several companies (including VMware) and independent development communities have created free, open source software that compares favourably to VMware’s offerings. We shall examine four such products: KVM, QEMU, VirtualBox and Xen.

VMware might surface as the world’s best third-party-supported software of its kind, but is it significantly better than the free alternatives? Our exploration will give you the opportunity to find out for yourself.

These solutions, like VMware, are all of the full virtualisation type. Full virtualisation means that each virtual machine (VM) receives its own complement of virtual hardware, usually consisting of a virtual hard disk, a virtual NIC, a virtual CD/DVD drive, a virtual CPU and a virtual display adaptor. Optionally, a VM may also have virtual sound devices, floppy disk drives, multiple CPUs, multiple NICs, multiple hard disks and serial ports (including USB). In a fully virtualised VM, you install an operating system to the VM’s hard disks just as you would to a physical machine’s disks. VMs can boot from their virtual CD/DVD drives or from ISO files.

Alternatively, you’ll hear this type of virtualisation referred to as host/guest virtualisation, which describes the relationship between the physical machine (host) that provides the disk space, network connectivity, processing power and other peripherals and the VMs that reside on it as ‘guests’.

Let’s get started with the Kernel-based Virtual Machine (KVM) over the page…

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