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 then one in Ruby, none worked well enough. They not fast enough or they were not reliable enough, or they were not transparent enough when things went wrong. Now we all love Ruby but good Rubyists know that it is not always the best tool for the job. After re-examining the problem we decided to rewrite the application in a mixture of Erlang and Ruby. By exploiting the strengths of both -- Erlang's astonishing support for parallelism and Ruby's strengths in web development -- the problem was solved. In this talk we'll get down and dirty with the details: the problems we faced and how we solved them. We'll cover the application architecture, how Ruby and Erlang work together, and the Erlang approach to asynchronous operations (hint: it does not involve callbacks). So come on by and find out how you can get these two great languages to work together.