CMPS 290S: Topics in Computer Systems
Spring 2002: Distributed Systems

This exam is optional; if you choose to do it, the exam will be folded into your class participation grade. The exam is due at 5 PM on Wednesday, June 5th by email to cmps290s@ethanmiller.com.

Your answers to these questions should be 2–3 pages long, and should show that you understand the question and the answer. You should cite any papers you reference directly, but you shouldn't need to do an extensive literature search to answer the questions. I am most interested in seeing how you think about the problem, not you collect other's thoughts on it.

The usual rules about cheating apply—cite your sources if you get specific information from them. You don't need to cite class discussions, but you should acknowledge help you get from others on this exam. Failure to do so will result in a zero score on the exam.

1. There is a fundamental tension between scalability and consistency in distributed systems—the more scalable a system is, the harder it is to maintain consistency. Using two different systems we discussed in class (naming, storage, peer-to-peer, etc.), show how this tension is addressed in the real world. Contrast the approaches taken by the two systems you examine.
2. A distributed system can be made reliable in one of two ways: relatively few more reliable individual components, or many less reliable components. What are the tradeoffs to each approach? Use examples from papers we discussed in class if you like.