Tropical storm Irene, which was downgraded from being classified as a hurricane before it reached the US East Coast on Sunday, appeared to have caused no major issues for data center providers in the affected areas, leading to little more than increased use of diesel fuel for backup generators.

No operators DatacenterDynamics contacted said the storm had caused downtime. Two companies – Digital Realty Trust and QTS – reported that their facilities had to be switched to generator power as a result of utility power outages, and the rest said their data centers continued operating normally.

Jim Smith, CTO at Digital, wrote in an email that some of the company's facilities lost primary utility power as a result of the storm. "These facilities successfully transferred to back-up power sources, which operated as designed and supported customer loads until the primary power sources became available again."

One Digital site in northern New Jersey continued running on generator power as of about 2:40 pm EDT on Monday, waiting for utility power to stabilize. "We are working with our customers to work out the timing for that transition back to utility power," Smith wrote. "We expect that to happen later today."

Digital contracted with Foster Fuels to secure additional fuel for the generators.

Another data center that lost utility power as a result of the storm was the massive QTS facility in Richmond, Virginia. Utility serving the data center is Dominion.

Brian Johnston, CTO at QTS, said the Richmond data center transferred to generator power without impacting its customers when its utility power feed was interrupted. "Diesel deliveries will continue to fuel the data center's generators until electricity is restored, ensuring our customers'mission-critical data is secure," Johnston said in an emailed statement.

The storm did not damage the data center's on-site substation.

Spokespeople for Equinix, Telx, Rackspace, SunGard, NTT America and Savvis told DatacenterDynamics that none of their data centers on the East Coast had lost utility power as a result of the storm and continued operating normally.

Dominion customers whose power Irene knocked out counted about 1.2m, the utility reported. Dominion said on Monday it had restored power to about half of them.

Con Edison, one of the region's major electric utilities said about 190,000 of its customers lost power as a result of the storm. Power was restored to nearly 60% of them as of 3:45 pm EDT on Monday.

PSE&G, another major utility in the region, had about 700,000 customers to restore power for. Electricity was back for about 500,000 of them as of 5 pm EDT.