Paxos lecture (Raft user study)

…study using CS students at two universities. We recorded a video lecture of Raft and another of Paxos, and created corresponding quizzes. This page makes our materials available for anyone interested. We think these are valuable resources for anyone learning consensus (whether Raft or Paxos or both). 0 - link Raft Video - link Paxos Video - link to this video…

…t basic form of Paxos, there is no concept of node roles or hierarchy like leader/follower, master/replica, etc. The base case is that all nodes have the same replicated log, and are "writers" capable of initiating changes to the log. This youtube video was particularly helpful in learning about consensus algorithms, specifically Paxos/MultiPaxos: link to this video John Ousterhout (author of Raft) walks through Paxos/MultiPaxos as outlined by Leslie Lamport, and then talks about a series of optimizations to improve performance. One key optimization is transitioning from performing consensus on a single log-slot proposal, to the entire log-slot altogether, which mitigates failed consensus rounds, and i…

…this support.) that said, raft has a lot of interesting applications, and, in my opinion, is definitely more understandable than the many versions of paxos. (implementing zab yourself, at this point, would be a futile exercise.) i found the videos from the raft user study to be very well done (and easier to understand than even their paper): raft: link to this video paxos: link ...however, i think they did paxos a disadvantage by not just focusing on multi-paxos (which is probably the most common implementation). but, it's certainly fair to say that info about paxos is spread out far and wide...with perhaps too many knobs to turn and implementation-related details to fill in yourself. as a side note:…

The first is a proof published in a paper that you can read. I recall the proof is for single decree paxos. In reality, you need multiple rounds. There are many subtle variations and I am not aware of a proof for that. Is an implementation correct? Frankly, that is a PhD thesis that is still to have been written. If you want to do a PhD and this topic burns inside you, go for it. Regarding consensus algorithm overview, no .. not that I know of. Here is a good video on Paxos: link to this video Enjoy my friend.

IMO if you develop a good understanding of Paxos then learn TLA+ you'll know everything you need to work on production distributed systems. Learn about CRDTs too, just to see what eventually-consistent systems look like. The real core of distributed systems is less knowing specific algorithms and more knowing what makes the field so hard, what solutions are possible, and the limitations of those solutions. For learning Paxos I like this video: link to this video Implement it yourself in your language of choice. For TLA+ there's the Practical TLA+ textbook or Leslie Lamport's video lecture series: link

Raft is very similar to Multi-Paxos. These Raft and Paxos user studies comparing the "understandability" of the two protocols might be helpful: link to this video (Paxos), link (Raft). See also, comparison of various "Paxos" implementations: link

At least for paxos this is more or less the standard method of explaining it, see: link to this video In paxos's case the logic is very, very simple - it's just the reasons for the logic are difficult to sort out. So teaching it iteratively works very well, because you show how simpler versions fail.