Virtualisation is now seen as essential in enabling organisations to manage their vital IT resources more flexibly and efficiently. Yet how challenging is it to successfully deploy virtualisation, especially at an SME? This guide, produced by Computer Weekly in association with IBM and Intel, covers the salient issues for an SME seeking to implement a virtualisation strategy.
Overview
Virtualisation is a growing trend in computing as organisations address the challenge of harnessing more processing power for more users, while reining in costs during the recession.
Surveys of SMEs conducted by IDC have revealed these businesses view virtualisation as presenting immediate cost advantages and opportunities to build and grow highly flexible IT environments.
IDC analyst Chris Ingle stresses that virtualisation is nothing new in the IT world, but the increased number of solutions now available for common, x86 servers means SMEs can do a lot of the things that previously only mainframe and Unix users could do.
"It democratises virtualisation and brings it within SME budgets and lets them do things that previously only larger companies could do," he says.
Choose the Right System
This presents valuable opportunities for SMEs to improve how they use resources and develop strategies for business continuity and disaster recovery, among other benefits.
But organisations need to consider carefully what they hope to achieve with virtualisation and choose the solution that best suits their needs. There are a number of different techniques for virtualising a server or building a virtual machine (VM).
Hypervisor Virtualisation
The most common is hypervisor virtualisation, where the VM emulates the actual hardware of an x86 server. This requires real resources from the host (the machine running the VMs).
A thin layer of software inserted directly on the computer hardware, or on a host operating system, allocates hardware resources dynamically and transparently, using a hypervisor or virtual machine monitor (VMM).
Each virtual machine contains a complete system (BIOS, CPU, RAM, hard disks, network cards), eliminating potential conflicts.
Common VM products include Microsoft’s Virtual Server and Virtual PC, along with EMC VMware’s range of products, such as VMware ACE, VMware Workstation and its two server products, ESX and GSX Server.
Risks & Benefits
For medium-sized organisations, virtualisation can lead to significant savings on equipment as well as more centralised management of what they have. It also allows them to harness and distribute greatly increased processing power very quickly.
The process of creating VMs is expected to get even easier for organisations, with Intel integrating improved virtualisation technology into its business-class processors. But this can be a double-edged sword. For instance, analysts warn that, because virtual environments are so cheap and easy to build, many organisations risk losing track of them.
New practices have to be put in place, responding to the increasing overlap in the internal areas of responsibility of the IT staff, as storage, server, and network administrators will need to co-operate more closely to tackle interconnected issues.
Virtualising at Operating System Level
One of the more commonly cited pitfalls of virtualisation is that companies can risk breaching software-licensing agreements as a virtual environment expands.
Without a method to control the mass duplication and deployment process of virtual machines, administrators will have a license compliance issue nightmare on their hands. Virtualising at the operating system (OS) level avoids this problem. Most applications running on a server can easily share a machine with others, if they can be isolated and secured. In most situations, different operating systems are not required on the same server, merely multiple instances of a single OS.
OS-level virtualisation systems provide the required isolation and security to run multiple applications or copies of the same OS on the same server. Products available include OpenVZ, Linux-Vserver, Solaris Zones and FreeBSB Jails. At first Linux-only, SWsoft recently launched its virtualisation technology for Windows. Called Virtuozzo, it virtualises the OS so multiple virtual private servers can run on a single physical server. Virtuozzo works by building on top of the operating system, supporting all hardware underneath. The VM does not need pre-allocated memory, as it is a process within the host OS, rather than being encapsulated within a virtualisation wrapper.
The upside to OS-based virtualisation is that only one OS licence is required to support multiple virtual private servers. The downside of this option is less choice, because each VM is locked to the underlying OS. In the case of Virtuozzo, it only guarantees support for Windows and RH Linux.
Paravirtualisation
Another approach to virtualisation gaining in popularity is paravirtualisation. This technique also requires a VMM, but most of its work is performed in the guest OS code, which in turn is modified to support the VMM and avoid unnecessary use of privileged instructions.
The paravirtualisation technique allows different OSs to be run on a single server, but requires them to be ported, that is they should know they are running under the hypervisor. Products such as UML and Xen use the paravirtualisation approach. Xen is the open source virtualisation technology which Novell is shipping with its own Linux distribution, SuSE, which also appears in the latest development of Red Hat’s Fedora, Core 4.
Server Sales Reach Tipping Point
IDC predicts something of an exodus towards virtualised server configurations over the next few years. The market analyst reported recently that the number of servers containing a virtualisation component shipped in Western Europe rose 26.5% to 358,000 units throughout 2008. IDC said these servers made up 18.3% of the market compared to 14.6% in 2007.
For the first time, last year the number of purely physical machines sold was eclipsed by sales of virtual- capable machines, which topped 2 million. IDC predicts declining IT hardware spending will result in VM sales exceeding physical machines by around 10% at some time during the year, and that the ratio of the two could be 3:2 by 2013.
In line with this trend, logical machines, or those with physical and virtual components, will realise a 15.7% increase over the same period. IDC notes that this highlights the importance to organisations of deploying the right tools to manage expanding virtual environments, seeing as both virtual and physical servers have to be operated, monitored and patched.
The research company also advises organisations ensure they have the right level of education if they are to properly exploit this new and potentially rewarding approach to corporate IT.
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