IT departments have been struggling with the impact of the prolonged heatwave on power supplies and datacentre cooling systems.
Last week EDF Energy interrupted power supplies in London's Soho, due to faults in its system which were exacerbated by high demand caused by the hot weather.
As Computer Weekly went to press, EDF said it was attempting to rectify the network faults, but said it could not guarantee that there would not be further outages as it did so. On Thursday businesses lost power for one and a half hours after shorter outages earlier in the day and businesses were bracing for a further one-and-a-half hour outage on Friday.
Major businesses and public sector organisations were warned of impending power cuts, but some still faced difficulties.
Jim Norton, senior policy adviser for e-business and e-government at the Institute of Directors, said, "We strongly recommend our members to have well worked out and tested business continuity plans and, where appropriate, to invest in multiple power feeds."
Paul Court, UK operations director at datacentre operator Globix, which has a site in central London, said, "We had a major problem with half an hour of outage." Fortunately, Globix had back-up generators.
Globix said it would be conducting a full investigation into the causes of the disruption and planned to inform its customers. These include Transport for London, online travel service Ebookers, pharmaceutical company Inpharmatica and financial services organisations.
Other organisations faced failures in their datacentre air-conditioning systems during the heatwave.
A local authority IT director said, "We had an air-conditioning unit fail in our computer room, which caused it to get a bit warm for a while. We switched-off non-essential servers, with minimal impact, and the unit is now fixed."
A leading media firm also had a server room air-conditioning unit fail, but it had back-up and was able to replace the unit with no impact on operations, the IT director said.
The problem of overheating datacentres has been compounded by the design of servers, according to Mick Dalton, chairman of the British Institute for Facilities Management and group operations director at datacentre operator Global Switch. "Modern server designs can restrict airflow to individual servers, around the racks and in the datacentre as a whole," he said.
IT directors can reduce the cabinet temperature of their racks by as much as 10°c simply by leaving the cabinet doors open. But Rakesh Kumar, vice-president at analyst firm Gartner, warned that this may not be practical in a high-security environment, such as financial services.