That’s a pretty big step up from a year ago, when Facebook engineers each tested out apps on just one smartphone — a problem considering different people used different smartphones, and apps run differently on each phone. That’s why Facebook built the new data center, which is made up of 60 custom-built racks, each of which holds 32 smartphones.
“As more people around the world come online for the first time, we want to make sure our apps and services work well for everyone,” explained Facebook product engineer Antoine Reversat in a blog post. “This means we need to understand the performance implications of a code change on both high-end and typical devices, as well as on a variety of operating systems.”
Most of Facebook’s apps run at scale, which means that each device’s configuration affects the app differently. That makes it extremely important for the company to test on as many different devices as possible — if the app doesn’t work properly on a specific device, that could turn off a ton of people from the app.
Interestingly enough, the majority of phones at the center are out-of-date models, including devices like an iPhone 4S and a Samsung Galaxy Nexus. That’s because Facebook is targeting its next billion users, who might not have as much money to spend on the newest phones out there.
While each rack currently holds a hefty 32 phones at once, according to Reversat the team wants to double that to 64 phones per rack. Not only that, but the company will also be sharing the designs for the rack, likely through the Open Computer Project that the company started back in 2011.
