StumbleUpon, the personalized web content recommendation engine eBay bought in 2007 only to be bought back by its founders two years later, has taken space at RagingWire's mega data center in Sacramento, California.

The company could not get the power densities and billing flexibility it needed with the two data center providers it had been using for the past two years or so, and, after an extensive search, settled with RagingWire – a company recently acquired by NTT Communications Corp., subsidiary of the Japanese telecommunications giant Nippon Telegraph and Telephone Corp.

Paul Hands, director of operations and infrastructure at StumbleUpon, said the Virginia data center the company has moved out of and the Santa Clara, California, facility it is in the process of moving out of, had old-fashioned infrastructure that did not satisfy its needs any more.

Hands said his many years working with data centers have made him very picky about them. Between 2007 and 2011, he ran all of Google's data centers outside of North America.

The most recent selection process for StumbleUpon started with selecting 20 providers, narrowing the list down to eight and going on a deep dive with each of them. RagingWire impressed him with its location in Sacramento – outside of the expensive Silicon Valley region but still a relatively short commute from the San Francisco Bay Area – the accessibility of the company's reps and technical information about the facilities and design of the infrastructure itself.

“RagingWire were fabulous at just showing us everything,” he said. “It's a fabulous design.

“Hundred percent uptime is what they're claiming and the record speaks for itself so far.”

The data center provider has patented an electrical architecture that enables it to have concurrent maintainability without the typical redundant infrastructure components, such as dual Uniterruptible Power Supplies. See an earlier FOCUS article that explains the technology in detail.

StumbeUpon serves its 30-plus million users with about 1,000 servers, Hands said. “Right now [at RagingWire] we have ample room for our 1,000 servers and a nice piece of headroom beyond that.”

He plans to add a secondary US site within the next 18 months or so, as well as a smaller presence outside of the country to support international growth. Mike Mayzel, the company's director of communications, says while most “stumbles” today are domestic, this is likely to change in the future.

“About 80% of our stumbles are from North America so there’s a big opportunity for us to grow internationally,” Mayzel says. About 40% of StumbleUpon's user traffic comes from mobile devices, and its recently released mobile Android application is available in eight languages.

NTT Comm. announced in late October a deal to acquire an 80% stake in RagingWire for US$350m.