I’m not aware of anything Discourse-specific, but there’s hundreds or thousands of opinions “out there” about how to scale Rails, PostgreSQL, and Redis, and Discourse is a fairly standard Rails/PostgreSQL/Redis application. As the person who is primarily responsible for the infrastructure here at CDCK, I’ve got to say that my job pretty much never involves worrying about scaling an individual site; my time is spent working on the problems of automation and scaling for the entire customer base. Rails+PgSQL+Redis just chugs along nicely all by itself.