Question: What Ruby on Rails deployment setup is best for good performance for a social networking website having 10,000 to 100,0000 users?

At Spark Solutions, we’ve scaled a Ruby on Rails app from 1000 to 300000 registered users, activity feed, over a 1 million visits and 500 000 sent messages between users a month.

We’ve started on a single VPS server and ended up on couple of dedicated machines. Some things we used:

• Nginx
• Memcached
• Varnish
• Phusion Passenger
• MySQL
• MongoDB
• Capistrano
• Sphinx
• delayed job for background processing (at that times it was the best solution)
• russian doll caching on every layer (model/controller/view/HTTP/static files)
• extensive use of rails counter cache
• running some requests without the full rails stack

Question & answer originaly posted on Quora.