Grig Gheorghiu wrote up a nice article on handling high traffic sites on EC2. It’s definitely worth a read for some high-level concepts about multi-tier architectures. It doesn’t talk deeply on details of EC2 (would have liked to see something mentioned about availability zones for MySQL and load balancers). One thing I really liked was the concept of using multiple load balancers with round-robin DNS pointing at them. I’ve been considering this as an option and have played around with HAProxy already. It’s likely a future step for our new image service at CafeMom.