More than 1,100 users lost their connection to a major US online backup service earlier this week just as the company completed work on a massive datacentre upgrade.
Events at Carbonite will act as a warning to IT professionals as analysts predict the market for hosted back-up services will treble in the next four years.
An unexplained bug caused users' connection to drop out, just as the service went live again after a scheduled maintenance outage.
Carbonite CEO Dave Friend said a software glitch caused the problem during the early hours of 9 March at the end of an expansion of Carbonite's IT operation – the first since 2006. "It was just one of those things," said Friend.
"The minute we reconnected to the internet, all of a sudden we had hundreds of thousands computers trying to talk to us at once. For some reason, [1,146] of them didn't reconnect. It didn't affect many people, but left things in a weird state that they couldn't recover from," remarked Friend.
Friend said all of the users affected by the "little glitch" had now corrected the problem by re-installing Carbonite's software via a download from the company's website.
Last month, Amazon's storage site also experienced an outage.
Although IDC expects online backup revenues to soar from US$235 million (£115 million) in 2007 to $715 million (£350 million) in 2011, the competition to attract SMB and corporate users to web-based back-up services is fierce.