Two years ago Rackspace had a problem: how do we backup 20K network devices, in 8 datacenters, across 3 continents, with less than a 1% failure rate -- every single day? Many solutions were tried and found wanting: a pure Perl solution, a vendor solution and one in Ruby, but none worked well enough. They were not fast enough, not reliable enough or they were not transparent enough when things went wrong. After re-examining the problem we decided to rewrite critical portions of the Ruby application in Erlang. This solution was a huge success. In this talk we'll get down and dirty with the details: why the solution was so successful as well as the problems we faced and how we solved them. We'll cover how we overcame the typical objections, the application architecture, where Erlang was a good fit and where it was not and how Ruby and Erlang work together.