Recent power outages at two separate datacentres have highlighted the necessity for firms to implement effective business continuity measures, and for IT managers to be more discerning about their service providers' back-up plans, according to experts.

On Sunday a datacentre in North London belonging to service provider Level 3 Communications suffered a power cut which lasted around six hours, while in the US, popular social networking site MySpace went down after the same problem affected its Los Angeles datacentre. UK Yahoo users also went without email and instant messaging services after a power failure.

Guy Bunker, chief scientist at Symantec, commented that the MySpace incident shows that firms must evolve their business continuity plans as they grow and consumer demand and expectation increases, and for global enterprises, " multiple datacentres must be in place should anything go wrong".

The Level 3 outage affected many firms, including IT Week publisher VNU, leaving customer websites out of action for up to 12 hours. According to virtual network operator Mnet, which uses the Level 3 datacentre, the firm's uninterruptible power supplies (UPSs) failed to start up when the local power substation suffered an outage.

Alan Rodger of analyst Butler Group said that firms must carefully consider the cost of their services going offline, against the cost of investing in solutions that provide more secure back-up procedures. "Customers should ask for back-up in their service level agreements (SLAs) because that level of outage is pretty unacceptable," he argued. "Hosting companies could provide switch-over to other datacentre facilities at a cost."

Graham Titterington of Ovum added that IT managers should be more discerning when asking their service providers what business continuity measures they have in place, and make other arrangements if these are not consistent with their firms' plans. "It's like IT security in that it's often a case of 'out of sight out of mind'," he argued. "If they outsource the [problem] firms think they can then forget about it."

But Mike Tobin, chief executive of datacentre operator Telecity Redbus, said that some customers have unrealistic expectations of their hosting service providers, especially given that many datacentres are reaching their capacity and heating up.