The long, slow oil price crisis that's been bubbling under -- and sometimes over -- since the Iraq invasion is starting to have an effect on the cost of server hosting. It's making the problem of balancing the pressure for computing throughput with the cost of powering server and data centres even more acute. As a result, at least one hosting centre has started to export the cost of powering its customers' servers.

What's happening is that the cost of electricity is becoming a more significant proportion of the cost of running such centres, as a result of both increasing oil and therefore electricity prices, and the ever-heftier power budgets of today's multi-core processors.

The consequence in at least one case is that hosting companies are starting to add fuel surcharges to their customers' monthly bills, airline-style. Europe-wide hosting centre specialist Redbus reckons that the price of powering its centres used to be bundled into the price but is now appearing on bills as a separate item, following a 52 per cent spike in power costs.

One Google engineer, whose employer runs one of the planet's more famous in-house data centres, said that the affordability of computing could, in future, be seriously affected by the spiralling cost of power consumption. He should know -- Google has complained before that its power bill will soon be outstripping the cost of the hardware that constitute its vast indexing systems.

So what's the industry doing about it? We've covered some ways in which AMD, Intel and others are aiming to cut the costs and power consumption of their chips, although the processor itself accounts for under half the overall power consumption of data centres, since CPUs are not the only heat generators in data centres, and each watt consumed requires another watt in cooling to remove the heat.

So while the processor vendors can and do have a significant effect on overall power consumption, they can't solve the problem on their own.

Keeping it cool
Those who can are data centre designers, aided by new technology. For example, Degree Controls is a startup whose innovative cooling system can, according to the company, cut the cost of air-conditioning by up to 30 per cent. It has, says Rajesh Nair, company founder and CTO, "attacked this problem by applying lessons learned from decades of experience in managing heat in extremely high power telecommunications systems."

The company's Adaptivcool system is built on a network of temperature sensors and fan-assisted perforated floor tiles, linked by what it calls thermal management software. It fixes the problem of localised hot spots through an understanding via sensors of where the heat's coming from, combined with the ability to direct cooling air to the appropriate place, dynamically, as equipment usage varies. It uses variable-speed fans embedded in the data-centre's raised flooring to achieve this, coupled with return passages that allow cool air to be directed as appropriate and hot exhaust air returned to the air-conditioning unit. The result is reduced power consumption, says the company, a service for which it charges from £60 per square metre.

But that's just one example, and re-engineering a data centre is not a trivial task. Looking further ahead, can we foresee a slowing in the rate of growth in power consumption? It seems unlikely. Although the processor MegaHertz count looks unlikely to increase significantly in the near to mid-term future, as the number of cores per die grows, so the transistor count will grow in accordance with Moore's Law, each semi-conductor consuming more power.

The best we can hope for is that CPU designers succeed in mitigating the effect of increased power by improved power management, as they've been quite successful at doing, if you look at the parallel increases in both laptop battery life and compute power. And with smarter cooling systems, the effects of increasing power consumption can be mitigated to some extent.

But one silver lining is that this trend is likely to result in the cost of computing becoming real: data centre managers will have a much clearer idea of the real costs of increases in compute power that are demanded from above. It might even get facilities and data centre managers talking to each other too...