From left to right, Instagram and Facebook engineers Pedro Canahuati, Patrick Bozeman, Rick Branson, Nick Shortway, Chris Bray, and Michael Gorven–part of the team that moved Instagram. And then moved it again Ariel Zambelich/Wired

Your Instagram photos aren't where they used to be.

This spring, even as some 200 million people were using Instagram on their smartphones, a small team of engineers moved the photo sharing service from Amazon's cloud computing service -- where it was built in 2010 -- into a data centre operated by Facebook, which bought Instagram in 2012. "The users are still in the same car they were in at the beginning of the journey," says Instagram founder Mike Krieger, "but we've swapped out every single part without them noticing."


Facebook calls it the "Instagration," and it was an unprecedented undertaking for Mark Zuckerberg and company. Facebook has moved other acquired properties like FriendFeed into its data centres, but typically, they were small projects that involved shutting a service down before moving it into the Facebook universe. The Instagram switch was the live migration of an enormous -- and enormously popular -- operation. "The service couldn't take any disruption," says Facebook engineer George Cabrera. Facebook won't say how many virtual machines were needed to run Instagram on Amazon, but it was in "the thousands." And the service now stores over 20 billion digitals photos.

The users are still in the same car they were in at the beginning of the journey, but we've swapped out every single part without them noticing.

The move also means that Instagram can more easily -- and efficiently -- connect to other services running inside the facility and other Facebook data centres across the globe. Most notably, Facebook has built sweeping systems for analysing massive amounts of data, and Instagram can now benefit from this "Big Data" infrastructure much like any other internal Facebook service. The company can also take advantage of a "spam fighting" tool Facebook built to weed out bogus posts.


But Krieger says Instagram doesn't really share data with the wider Facebook operation. He indicates, for instance, that Facebook can't use your behaviour on Instagram to target ads on Facebook proper -- or vice versa. "One of the things we had to do was really silo the information, which ends up being important for privacy and other reasons," he says.

The Instagration is by no means typical. For Adrian Cockcroft, who once oversaw cloud infrastructure at Netflix and now follows cloud computing at VC outfit Battery Ventures, the world is moving onto the cloud, not off it. "If you get to be Facebook's size, you want your own data centres," he says. "It doesn't make sense for most little companies." But as they grow, some outfits, such as gaming company Zynga, have moved large parts of their operation off the cloud and into private data centres, mainly to improve costs. And you can bet that others will do so in the future -- particularly if they're acquired by Facebook.

This article originally appeared on Wired.com