Operating at Facebook scale is far from trivial. With 1.49 billion monthly active users (and growing 13 percent yearly), every 60 seconds on Facebook 510 comments are posted, 293,000 statuses are updated, and 136,000 photos are uploaded. And there lies the challenge of serving the masses efficiently and reliably without any outages.

Related Articles:
http://highscalability.com/blog/2016/1/13/live-video-streaming-at-facebook-scale.html