It's been a while since we stood back and examined the virtualisation market and technology -- which remain one of the most interesting areas of the industry today, although it's showing signs of growing pains. One thing's for sure: the next couple of years will be crucial for today's established players.

Virtualisation technology

Where are we now?

All the headliners from last year are still here. VMware leads the market and has continued to innovate, although the pace has slowed somewhat as it seeks to recoup its huge investment in industry-defining technologies such as its ESX Server hypervisor.

However, in terms of visibility, other virtualisation technologies are making more inroads -- although it's hard to pin down exactly how much of this is translating into hard cash in the developers' pockets. This is especially the case as much virtualisation software -- such as Xen -- has been developed as open source.

So there are strong indications that there's a good deal of virtualisation being deployed among developers and enthusiasts as a result of the software infrastructure's ready availability, but when it comes to sizeable enterprise deployments, VMware remains favourite -- effectively the default choice. We covered the case of HSBC, which last year consolidated almost 1,000 servers into 300 physical machines using VMware technology, for example.

SWsoft, which claimed that revenue from its Virtuozzo and Parallels virtualisation product lines grew a massive 734 percent in 2006, is making a strong case for being second behind VMware -- a situation it may retain until Microsoft arrives -- late again -- with its Viridion hypervisor in 2008. SWsoft differentiates itself with technology, eschewing VMware-style hardware virtualisation in favour of OS virtualisation.

The main plus point is that it offers better performance, since the software doesn't virtualise the hardware. The downside is that it involves each guest sharing the kernel of the underlying OS, so both host and guest OSes have to be identical. The company's also been focusing on making partnerships, including a bundling deal with Novell's SuSE Enterprise Linux, and a tie-up with HP's Proliant partner programme, both in March 2007.

Also in the hunt for a share of VMware's revenue is a more recent entrant, Virtual Iron. However, according to Owen Garrett, product manager at Zeus Technologies, which positions itself among VMware's ecosystem vendors, no company other than VMware is making any impact on the enterprise server virtualisation market. "It's the safe choice," says Garrett.

Illuminata analyst and virtualisation specialist Gordon Haff says that, while "SWsoft has been doing quite well it's a different product [from VMware's] for at least somewhat different needs. Virtual Iron is relatively new so it's too early to say."

At the high end, Sun's Solaris containers are not perceived as mass market technology. However, if Sun is to be believed, Solaris is making inroads into the high-end Unix space, as IBM and HP wind down their Unix development efforts and the vacuum is filled by Solaris bundled with the hardware.

Drivers

Driving the market are the same forces as were pushing it along a year ago. Key among these is the potential for cost savings by consolidating physical servers. Load up a big server with multiple virtual servers that each run one or at most a small handful of applications, and you save admin time, as well as cutting down on energy usage for power and cooling.

The number of real world case studies that have emerged in recent months suggest that server consolidation using virtualisation is both desirable and possible -- but that you do have to develop a detailed plan before you start, and that your servers have to be well-organised beforehand.

So much is commonplace -- and much more can be found on the vendors' websites.

Barriers

However, it's also the case that a number of pain points have become evident. The first is that, whether an OS is open source or proprietary code, additional costs include either support subscriptions or software licences respectively.

Gartner has also raised the spectre of security. The research and analysis company said recently that a combination of immature security tools for virtualised environments and a failure to set and implement policies to protect virtual servers could result in their being less secure than physical equivalents.

We're hearing more too about virtualisation projects being impeded by politics -- specifically, departments unwilling to give up their physical assets, and who see their applications being packaged up in a VM inside a big box as a loss of control.

Then a lack of communication between facilities managers and the data centre can often result in projects being held up simply because of physical constraints -- mainly those around the ability of the infrastructure to deliver enough power.

And consolidation doesn't eliminate administrative costs -- in fact, larger servers often take more admin than smaller ones. In particular, loading up a server with a dozen VMs means there are a dozen operating systems to patch and maintain. This means VM management becomes a huge issue, as Haff points out. "One of the realisations that many people are coming to is that management and provisioning software is an essential part of the mix. Carving up machines is all well and good but without proper administration tools you're left with more operating system instances than before -- and you haven't necessarily saved a whole lot of management effort relative to the prior server sprawl -- plus you have another layer of software to learn to use."

Garrett adds: "Virtualisation is only using 20 percent of its potential -- the rest is management." However, it would appear that the upsides outweigh the downsides, especially at a time of rising energy prices and increasing awareness of green issues.

Alternatives

Virtualisation has come to mean the abstraction of the hardware from software but that's quite a narrow definition, as Haff points out: "Note that "virtualisation" refers to a whole class of technologies of which virtual machines, that is, 'server virtualisation', is just one. Virtualisation more broadly refers to any remapping of physical resources to logical ones anywhere on the stack.

"Thus it also includes operating system containers such as those from SWsoft and Sun and the various forms of application virtualisation such as Trigence AE and Microsoft SoftGrid. It also includes many things that we don't even think of as virtualisation anymore because they're so commonplace, such as file systems."

The latest in application virtualisation is delivered by start-up company FastScale. Its product, Composer, allows IT managers to package applications with just those elements of the OS that the application requires. The result is a bundle which can be as small as just one percent of the standard combination of OS and application, which helps minimise hardware resource utilisation.

Others have been here before, including SoftGrid by Softricity, which was bought by Microsoft last year. This changes applications into network services that no longer need to be installed, says the company, but instead delivers them as a service. Trigence’s AE packages up applications and their dependencies and creates independent moveable objects, says the company. Altiris' technology offers similar benefits.

Future possibilities

In the short term little seems likely to change. However, the mainstream virtualisation market will see a big shake-up when Microsoft's hypervisor, codenamed Viridian, arrives sometime in the first half of 2008.

Redmond will arrive in a market that's already semi-mature, with open source players such as Red Hat and Novell as well as VMware, already shipping product at zero upfront cost -- not a situation to which Microsoft is accustomed. Nevertheless, there's no doubt that this will energise the market and provide comparisons and choices for users that today's vendors have not yet had to suffer.

You can expect other changes too, according to Garrett. "Microsoft's licensing model of the OS inside of VMs will change to accommodate virtualisation as soon as it has a product in the market", he said. As to which OS that might be, Garrett suggested that if he were in Microsoft's shoes, it'd be a light version of Vista.

Meanwhile, as Garrett says: "VMware is sticking to developing its functionality and enlarging its ecosystem" as armour against Microsoft.

What happens after that depends on just how good a job Microsoft has made of developing compelling new technology. As ever, it's not first in the market but, when it does arrive, having examined the competition very closely, you can bet that it's product will capture significant market share.

It's just a question of how long that takes.