Virtualisation is the biggest trend in the server market right now -- and with good reason. Driven by the growing cost of power, of server administration and of floor space, consolidating servers by virtualising them is proceeding apace. All hardware vendors report very keen interest from enterprises large and small for this technology.

Yet there are many ramifications to the virtualisation trend, many as yet unexplored. Server consolidation is not the only benefit conferred by virtualisation. Desktop support, the management nightmare that used to be headline news, has faded into one of those dull issues that enterprises seem to have decided they can manage, albeit resentfully. Virtualised appliances – virtual machines set up to do a specific job – could well bring desktop support back to the top of the IT admin agenda – but in a good way.

How so? VMware has just launched a $200,000 Virtual Appliance Challenge to promote innovation in this field and the momentum behind virtual appliances is growing rapidly. When first launched on 1 March 2006, there was only a handful of virtual appliances linked into VMware Web site. Now there are dozens and the number grows daily.

The range of appliances started small – installs of various free OSes, which at least saves having to install the things. But the offerings are not just free software in an installed and running package any more. It's since grown so that there are some seriously useful packages there, including VoIP servers, enterprise desktops, development platforms and even a document repository. BEA has developed a WebLogic platform for enterprise integration, both IBM and Oracle have put up installed and working versions of their enterprise-level databases, and a number of security vendors are offering firewalls and intrusion detection/prevention systems, all ready to go. In addition, there are messaging systems, traffic management platforms, and more.

The advantages for admins of virtual machines (VMs) are fairly obvious: a VM is a great sandbox within which to test systems, configurations and applications without the risk of breaking a working system. And if it all goes pear-shaped in a major way, you can just revert to the original or the last snapshot and start again, no harm done. It's hardware-independent too, allowing the process to be carried out pretty much anywhere on any machine.

According to VMware's Richard Garsthagen, the Oracle VM mentioned above has been downloaded over 40,000 times -- "a massive number for application like that". There have been over a million downloads so far, said Garsthagen.

Back end systems benefit, but this trend also allows IT departments to provide end users with tested and locked down versions of their desktops. Running full-screen, maybe even on a Linux host OS, the end user need be none the wider that they're in fact running on a virtual system, with all the benefits that implies. It's a known environment, reducing support issues and with hardware independence too. And with the trend of re-centralisation within the enterprise, a VM makes a good platform for serving a thin client with a desktop system.

So what's not to like? VMs can get pretty big and cumbersome to move around -- some are 1GB or more -- and only modern hardware makes the most of them from a performance perspective. Also, the virtual world, while getting more crowded by the week, remains almost a one-company business.

This does not appear to be a problem for enterprises, however, since market leader VMware and its customers are fully aware that Microsoft is on its way. Since the acquisition of Connectix, Redmond has been evangelising the virtualisation story. And while its software has been pretty clunky and limited so far, that's set to change. But VMware is leagues ahead already in terms of customer base, community loyalty and technology development, and looks set to stay there at least into the mid-term future -- and after that, who knows?

With current technology allowing administrators to move VMs across servers within data centres to where processing and storage are available, and after that, between data centres, what started as a virtual machine challenge could grow into a global grid. There's a lot up for grabs.