This is the second in our series of presentations from SCALE 12x. In addition to Dru’s talk (ZFS 101), John Hixson, Senior Software Developer at iXsystems, also gave his talk “Introduction to FreeNAS Development”. FreeNAS has been around for several years now but development on it has been driven by few people. Even with corporate sponsorship and a team of full time developers, outside interest has been minimal. Not a week goes by when a bug report or feature request is not filed. Documentation on how to develop on FreeNAS simply does not exist. Currently, the only way to come up to speed on FreeNAS development is to obtain the source code, read through it, modify it and verify it works. The goal of this paper is to create a simple FreeNAS application to demonstrate some of the common methods used when dealing with FreeNAS development, as well as showcase some of the API. We’ve made a video of John’s talk available on YouTube. The corresponding slides for his talk can be found below.