here is the video from erlang-factory 2012 which kind of goes in more depth (and width) : <a href="http://vimeo.com/44312354" rel="nofollow">http://vimeo.com/44312354</a>. the pdf for the talk is available here: <a href="http://www.erlang-factory.com/upload/presentations/558/efsf2012-whatsapp-scaling.pdf" rel="nofollow">http://www.erlang-factory.com/upload/presentations/558/efsf2...</a>