A heat wave in the US this week pushed energy demand to record-setting levels and caused brownouts and scattered outages in some regions -- and put data centre managers on guard for problems and re-emphasised the need for strategies to deal with data centre heat issues.

Data centres are generally well prepared for these extremes with uninterruptible power supply (UPS) systems and generators, but the stress that a heat wave puts on power supplies can still reveal heretofore unknown issues. That's what happened to Kern Weissman, director of infrastructure and network systems at CD&L, a logistics and delivery company.

Power supply problems in New York this week affected a three-phase power supply at a secondary data centre in CD&L's Manhattan office. But the UPS system didn't immediately alert the IT staff to reduce voltage on one of the phases. "The heat wave exposed an area of risk that I hadn't considered," said Weissman. There was no system downtime, but new automated alert procedures were quickly established, he said.

Unfortunately, there wasn't anything Weissman could do about the brownout affecting his Queens home, which was into its third day today. "The majority of sockets in your house get low amperage and low voltage," said Weissman. "I only have two active full sockets that are working -- it's pretty miserable."

As with many energy providers, the relentless heat has Xcel Energy, a Minneapolis power company with some 1.5 million customers, breaking demand-generation records. It reached a record peak demand on July 14 of 8,622 megawatts; the previous record of 8,596 megawatts in peak demand was set in 2004, a utility spokeswoman said. The heat was causing some outages, and Excel was asking business customers such as Slumberland to help cut usage.

Slumberland operates 100 furniture stores in 10 states. To help Xcel meet demand, it removed its corporate headquarters, distribution centre and a retail outlet from the power grid and supplied power to them via a generator during the worst of the heat wave, said Seth Mitchell, infrastructure team manager.

The data centre remained connected to the power grid and was unaffected by the heat, said Mitchell. The company is using American Power Conversion monitoring and UPS hardware and can switch over to a generator in 12 seconds if needed. The company is seeking more protection from energy problems, began installing a second air cooling system in its data centre this week and has plans for second generator. "Pretty much every year, the power in this season is not reliable," said Mitchell.

Dealing with heat also means containing demand, and that's one of the reasons why insurance provider Aflac is moving toward virtualisation.

"We're trying to have zero server growth while meeting the needs of a growing business, and we think that is achievable," said John Blalock, senior manager of distributed server management at Aflac. The company has about 620 physical x86 servers and has moved its development and disaster recovery operations into virtualised environments, something it will eventually do with its production servers as well.

"I think the benefit will be in manageability and containing the cost of managing the physical boxes," Blalock said.

Power reliability problems will increase for data centres because reserve electric capacity is declining nationally, according to Kenneth Brill, executive director of The Uptime Institute. He said the US is not investing enough in building new power generation capacity, and the message for data centre managers is: "You'd better know that your engine generators work."

Another thing that data centre managers can do is investigate whether their cooling systems are delivering at their rated capacity, said Brill. He said half of the cooling units do not work efficiently for a variety of reasons, including clogged filters, belts slipping and refrigerant that's not fully charged. If the air cooling system isn't meeting a data centre's needs, "the day they would discover that is on a hot day," said Brill.

And while the UK is not as dependent on air-conditioning as the US, the trend is upwards -- what happens there will happen here...