Temperatures in the high 90s, and exceeding 100 degrees in some areas, caused the Electric Reliability Council of Texas, the organization that runs the state's energy grid, to issue an emergency call to power companies, cutting off electricity to thousands of Texans with the rolling blackouts that affected homes and businesses.

According to representatives for ERCOT, power consumption in Texas peaked at 52,000 megawatts on Monday, while typical consumption for April is 40,000 megawatts. One megawatt, one thousand watts, is considered roughly enough energy to power the peak need of 500 houses.

The jump in power consumption was due to unseasonably hot weather. A reported temperature of 101 degrees at the Dallas-Fort Worth International Airport broke the previous high of 94 set in 1913 and matched in 1925.

While residential users saw air conditioners go down, and traffic backed up at streetlights, local Web hosts say their data centers - obviously big draws on the power grid - are well prepared for outages.

"As a data center provider, we will always make sure we have the ability to sustain ourselves through any public utility issues," says Michael Landesman, VP of infrastructure operations at San Antonio-based managed host Rackspace (rackspace.com). "We don't want to be at the mercy of anything they're doing. Which means that if there is a power problem, regardless of whether it's over utilization, they've oversubscribed or whether they just have a local issue, we will always be able to generate and sustain our own power."

Part of preparing for disruptions in this kind of service, say Web hosts, is realizing that power outages can happen without warning, as in the case of Monday's rolling blackouts.

"I called our TXU [the local power company] rep earlier today to see if there was any change as far as how they make the decision to cause blackouts and if there's any kind of public announcement that is made," says Tim Connolly, director of Technology at Dallas-based Web host The Planet (theplanet.com). "In fact, I didn't learn what ERCOT's timing was, the actual schedule of events, until the media release came out, which I think was late last night."

Dealing with an unexpected break in power supply, says Landesman, requires automated processes for switching to generator power.

"We all have UPS," he says. "Most of us have generators and fuel storage to get us through a crisis. The problem with things like rolling blackouts and any kind of a critical grid problem is that we don't know they're coming. If you have a system that's based on any manual interaction, then you're putting your customers in your data centers at risk. All of our Rackspace facilities handle that transfer to generator automatically. Once an automatic transfer switch notices there's no more utility power, it automatically fires the generators up, spins them up to test that they're providing quality power and transfers our load to it and will stay there until that grid comes back up for at least 15-30 minutes."

Monday's rolling blackouts, however, were a preventative measure, meant to conserve power and prevent an actual outage. They were limited to the ERCOT grid, which services about 80 percent of the state. Service was back to normal by Monday evening, says the group.

As a preventative measure, says ERCOT, the blackouts were a success. They prevented any serious region-wide outages from taking place

As heavy consumers of power, data center operators can also help to reduce the load during periods of particularly heavy demand.

"ERCOT has a program called LAARs, a program where the ERCOT council will instruct subscribers to the LAARs program to go offline," says Connolly. "Bascially with that LAARs program, they instruct our power switching to switch over to generators and take our load off the grid, so it helps the grid. Some of the larger consumption facilities are looking at that as an option because it's much more convenient to switch to generator power when somebody's standing there watching. It's kind of a unique project, but it seems to be working, because I noticed in their announcement they mentioned that LAARs was activated yesterday."

Despite the unusual conditions, the rolling blackouts in Texas do not appear to have caused any outages at Web hosting providers. And the weather is expected to return to normal temperatures in the 70s by midweek.

Web hosts say they don't have any serious concerns about the availability of power in Texas.

"All states have their own unique challenges to power distribution, cost and PUC issues," says Landesman. "Right now I'm not experiencing any concern about Texas in general. We have facilities in Dallas and in San Antonio, and I'm not concerned about what they can deliver. I do know that they're expanding the power grid and doing what they can to provide it. My concerns with the cost of that power are always there."