Phone screen: Discussed my experience and interests. Questions on fundamentals like data structures, run time complexities and operating system internals. On site: 6 technical rounds and a lunch session with the hiring manager. More operating system internals, file system internals, computer architecture, distributed systems, coding, data structures, complexity analysis, design choices, past projects and challenges encountered, producer-consumer variations, multi-threaded programming related and such. Overall, I'm very impressed with the team and the interview process. Felt like the evaluation is more thorough unlike many other places I've interviewed in the past.