Social media site Twitter blamed its outage, which occurred on 26 July, on a double failure in its data center.

Millions of users were left without services on Thursday last week.

Twitter VP of engineering Mazen Rawashdeh said the glitch was fixed by 7:25pm GMT.

The outage occurred after a data center system and its backup failed at the same time – an event Rawashdeh described in a blog post as an “infrastructural double-whammy”.

"Data centers are designed to be redundant: when one system fails, as everything does at one time or another, a parallel system takes over,” Rawashdeh said.

“What was noteworthy about today's outage was the coincidental failure of two parallel systems at nearly the same time.”

The outage occurred the day before the opening of London’s Olympic Games – which Twitter will play a part in, with the London Eye observation wheel turn into a giant mood ring to project positive and negative tweets as they occur.

The project was put together by a team of MIT graduates that work in linguistic analytics.

Hosting.com’s outage

According to Wall Street Journal blogger Joel Schectman, US hosting provider Hosting.com suffered an outage that affected more than 1,147 customer sites last Friday for up to five hours.

According to the blog, the incident happened as an engineer was performing maintenance at a server site in Delaware. He accidentally cut the power to the facility.

Schectman quoted Hostint.com CEO Art Zeile in his piece, who said that while the power loss only lasted minutes, servers needed restarting which extended the time the site were down.

He said backup was provisioned, but only for customers who chose to add it as an additional service.