cop5615fa11quiz3key - Quiz 3 Key COP 5615 Fall 2011 1 a...

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Quiz 3 Key COP 5615 Fall 2011 1) a) Compare the fault tolerance of the Lamport DME solution with the coterie- based solution. b) In each case, what would a process have to do to recover from message failure? c) From node failure? 2) a) In what ways are leader election and DME similar? b) In what ways are they different? Explain. KEY 1) a) Lamport DME requires that the process receive votes from all other processes, whereas the coterie-based solution only requires that the process receive votes from its quorum. A process failure that is not in the quorum will not affect a process in the coterie-based approach. In both cases, message failure will lead to a process waiting for a message that never arrives (either because the request was lost or the response was lost). (2 pts) b) For Lamport voting DME to recover from message loss of the request or the vote, the entering process can re-send the request. A voter just has to note the process to whom it has given its vote, and re-send the vote if that process re-sends its request. We can introduce a
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