Chris Miller

So DAS was always going to be a motherfucker! Whilst reading through the notes I realised: I knew nothing in depth about this course, I was boned.

Then PD pulls off an exam which was, not easy, but not the complete enema which I was expecting.

So the exam wasn’t easy as I said, but I managed to do some of the questions, unlike I had expected – I even did the programming question!

Question 1

• A – Define interfaces/classes for a remotely-accessible membership service [12]
• B – Lamport clocks, illustration of wrong orders amongst messages [7]
• C – Token-passing, failure modes, impact on dissemination of messages [7]
• D – Vecotr clocks, description and how it doesn’t solve the ordering problem [4]

Question 2

• A – Spanning trees, building a spanning tree [7]
• B – Description of problem efficiently solved with spanning trees [7]
• C – Spanning trees vs. diffusion trees [4]
• D – Wave vs. Traversal algorithms, either totalling values or finding maximum in a 2-D torus [12]

Question 3

• A – Large-scale distributed file systems, problems, solutions, trade-offs and design issues [23]
• B – Problems when implementing a CMSS [7]

Question 4

• A – Distributed workflows using tuple-spaces. [10]
• B – 2 aproaches to leader election with a tuple-space [10]
• C – Different ways a Byzantine node can disrupt distributed tuple-spaces [3]
• D – Why if > N/3 Byzantine nodes cannot have consensus on common value [7]

I managed to do question 2, which I felt most comfortable then questions 3 and 1. I didn’t have a clue about tuple spaces, having briefly read the notes on them and not feeling too confident about how to use them, there was no way I was going to do a whole question which centered around them!

Anyway, not as bad as it could have been. But then again, I said the same about OS3 last year and it didn’t turn out too well for me! Hope everyone else did shit, and thus making my grade slightly better!
- Chris