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Paxos
Jingguo Yao edited this page Sep 24, 2015
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In a synchronous system, there are bounds on:
- Time of computation
- Time of message deliver
An asynchronous system is one that is not synchronous.
- Safety
- Not liveness
A walk-through of Paxos Made Simple.
- Describe a scenario for not being liveness.
- What is the commit point? After the commit point, how is the chosen value is ensured to be chosen?
Questions in 6.824 Lecture Notes and 6.824 Paper Question
- Recite how P2c ensure P2b?
- Why "To maintain the invariance of P2c , a proposer that wants to issue a proposal numbered n must learn the highest-numbered proposal with number less than n, if any, that has been or will be accepted by each acceptor in some majority of acceptors".
- Why "Note that the proposer can always abandon a proposal and forget all about it—as long as it never tries to issue another proposal with the same number"
- Why "The leader could take the next two commands requested by clients to be commands 136 and 137."
- Why the extra instance of Paxos in Section 5.1?
- How does the master lease works in Section 5.2?
- How to expend the concept of leases to all replicas?
- Why Epoch numbers? SCN Three acceptors: 1, 2, 3. Acceptor 1 accepts (n_a=1, v_a=A). Then the proposor dies. Another proposor start a new Paxos. If it proposes to 2 and 3, it can chose a new value. If it proposes to 1 and 2, it will learn (v_a=A). Is this scenario correct?