What I like about them is that they post their approaches to certain challenges they run into on their blog. For the past few years, they have posted about their amazingly popular and awesome “storage pods” which make up the majority of their infrastructure. And I mean they give pretty much all the details so you yourself can build it!! Here are the links to each iteration they have created!
Part I: 67TB
Part II: 135TB
Part III: 180TB
Enjoy! This post will stay updated if any new ones come out!