Seven steps to a green datacentre

Datacentre power consumption is a big problem for IT managers wrestling with increasing energy costs and growing concern about the environmental impact of ever-growing energy use. But there are steps that can make your datacentre leaner and greener


How green is your datacentre? If you do not care now, you will soon. Most datacentre managers have not noticed the steady rise in electricity costs, since they do not usually see those bills. But they do see the symptoms of surging power demands.

High-density servers are creating hot spots in datacentres that have surpassed 30kW per rack for some high-end systems. As a result, some datacentre managers are finding they cannot get enough power distributed to the racks. Others are finding they cannot get more power to the building: they have fully tapped the utility company's ability to deliver additional capacity.

The problem already has the attention of Mallory Forbes, senior vice president and manager of mainframe technology at US bank Regions Financial. "Every year, as we revise our standards, the power requirements seem to go up," says Forbes. "It creates a big challenge in managing the datacentre because you continually have to add power."

Energy efficiency savings can add up. A watt saved in datacentre power consumption saves at least a watt in cooling. IT managers who take the long view are already paying attention to the return on investment associated with acquiring more energy-efficient equipment. "Energy becomes important in making a business case that goes out five years," says Robert Yale, principal of technical operations at investment management firm Vanguard Group. His 60,000 square foot datacentre caters mostly to web-based transactions. While security and availability come first, he says Vanguard is "focusing more on the energy issue than we have in the past".

Green datacentres do not just save energy, they also reduce the need for expensive infrastructure upgrades to deal with increased power and cooling demands. Some organisations are also starting to take the next step and are looking at the entire datacentre from an environmental perspective.

Following these steps will keep astute datacentre managers ahead of the game.

Consolidate servers, then consolidate some more

Existing datacentres can achieve substantial savings by making just a few basic changes – and consolidating servers is a good place to start, says Ken Brill, founder and executive director of the Uptime Institute consultancy. In many datacentres, he says, "between 10% and 30% of servers are dead and could be turned off".

Cost savings from removing physical servers can add up quickly - up to £600 in energy costs per server per year, according to one estimate. Mark Bramfitt, senior programme manager in customer energy management at US energy supplier Pacific Gas and Electric, adds that the money saved in power use is matched by savings in cooling costs. The utility firm offers a "virtualisation incentive" scheme that pays up to $300 (£150) per server taken out of service through server consolidation.

Once idle servers have been removed, datacentre managers should consider moving as many server-based applications as possible into virtual machines. This allows a substantial reduction in the number of physical servers required, while increasing the utilisation levels of remaining servers.

Most physical servers today run at about 10% to 15% utilisation. Since an idle server can consume as much as 30% of the energy it consumes during peak use, so increasing the utilisation levels offers more for the money.

To that end, virtualisation vendor VMware is working on a new feature associated with its Distributed Resource Scheduler that will dynamically allocate workloads between physical servers that are treated as a single resource pool. Distributed Power Management is designed to squeeze virtual machines on as few physical machines as possible, and to automatically power down servers that are not being used. The system makes adjustments dynamically as workloads change. In this way, workloads might be consolidated in the evening during off-hours, then reallocated across more physical machines in the morning, as activity increases.

Turn on power management

Although power management tools are available, administrators today do not always make use of them. "In a typical datacentre, the electricity usage hardly varies at all, but the IT load varies by a factor of three or more. That tells you that we're not properly implementing power management," says Amory Lovins, chief scientist at the Rocky Mountain Institute, a US energy and sustainability research firm.

Just taking full advantage of power management features and turning off unused servers can cut datacentre energy requirements by about 20%, he adds.

This is not happening in many datacentres today because administrators focus almost exclusively on uptime and performance, and IT staff are not comfortable yet with available power management tools, says Christian Belady, technologist at Hewlett-Packard. He argues that turning on power management can actually increase reliability and uptime by reducing stresses on datacentre power and cooling systems.

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