Distributed Systems 6.2: Raft

This video is part of an 8-lecture series on distributed systems, given as part of the undergraduate computer science course at the University of Cambridge.

[dmytrostepanyshchenko]

Thank you, Martin, for such an amazing trip through such a complex topic like consensus algorithms.
This part was omitted in the "Designing Data-Intensive Applications" book and I am really happy that you continue sharing the knowledge by the Youtube channel.

Good luck with your research!

[zhouyuan]

Node state transitions in Raft [0:01]
Follower, Candidate, Leader
Raft(1/9): intialisation [3:42]
currentTerm, votedFor, log, commitLength -> on disk
1st leader election [7:11]
Raft(2/9): voting on a new leader [9:28]
Raft(3/9): collecting votes [12:56]
Raft(4/9): broadcasting messages [16:31]
Raft(5/9): replicating from leader to followers [19:23]
Raft(6/9): followers receiving messages [21:31]
Raft(7/9): updating followers' logs [26:24]
Raft(8/9): leader receiving log acknowledgements [30:14]
Raft(9/9): leader committing log entries [33:28]

[hpandeymail]

You are so good .. I love you. Namastey from Bangalore 🙏🌷

[jRsqILVOY]

How do you deal with quorums in the case of a dynamic number of nodes? I.e. in a Peer-to-Peer application where peers can suddenly disconnect (possibly without sending a leave message, etc.), and later re-connect. if a lot of nodes suddenly disconnected, then we could end up with less than a quorum of nodes remaining if they don't update the necessary quorum.

Perhaps lowering the quorum limit in the case of repeated failed elections?

[yueliang]

will the term number overflow if it is an integer or long number? how to solve the issue?

[tce]

What if the Candidate is not able to get a quorum of votes for multiple terms? The probability of this occurrence is super low, but just wanted to know if this would be some sort of "stale mate". 🤔

[alvin]

What happens if the leader crashed during the total order broadcast?

[tszwangchiu]

Say Hi to MIT distributed systems students 😂