Facebook: VP of Technology talks about how Facebook works…

October 15th, 2009

Scalability is often one of the biggest challenges you can face, when you website grows – it often grows *very* quickly. To produce systems and architecture that scale with your growth is usually spectacularly complex and expensive. When you’re talking about a site with 300 million users, that’s really only about 5 years old, you have a pretty fascinating case study. Follow the link to hear how Jeff Rothschild describes how Facebook meets the challenges in his presentation entitled High Performance and Massive Scale


Key stats from the presentation about Facebook’s infrastructure/scale include:

  • Facebook has 30,000 servers supporting its operations*
  • Facebook stores 80 billion images (20 billion images, each in four sizes
  • Facebook serve up 600,000 photos a second
  • Facebook creates 25 terabytes of data per day in logging data into a Hadoop cluster
  • Facebook services about 120 million queries to it’s Memcache per second
  • Facebook has c. 230 Engineers, which is a ratio of roughly 1.1 million active users per Engineer
  • Facebook operates a shared nothing architecture wherever possible
  • Facebook’s development of php, mysql, memcache and various others, has virtually all been made open source
  • Facebook sends over 1 billion outbound (transactional, typically notifcation) emails per day

* Changes daily. The bulk of which is webserver to handle the low runtime efficiency of php.

One of the most interesting developments for anyone currently using php in a commercial environment is Facebook’s current development of a php compiler, which they estimate will give them 50 – 70% increase in runtime efficiency, this might give them a small amount of breathing room in terms of current server requirements. More interestingly for the wider php community, if this complier is made open source (which I’m absolutely sure it will) it could give php a real boost in the popularity stakes.


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