[dunkelheit]

Kudos to the raft authors for making distributed consensus accessible. Structuring the presentation in terms of RPCs and making the algorithm well-suited for implementing replicated state machines may not sound like a big deal, but those decisions really helped to make it approachable.

In a span of a decade consensus transformed from an esoteric algorithm that you can maaaaybe try implementing if you are a google engineer, to being widely deployed across many storage systems and readily accessible libraries and Raft played a big part in it.

[almostgotcaught]

> if you are a google engineer

Do people really have this kind of inferiority complex? What exactly do you think Google engineers are? People with 5 eyes and for hands with 10 fingers each? They read the papers (Paxos or whatever) struggle to understand it, implement beta versions, and iterate just like everyone else.

[eatonphil]

Anyone can implement Raft. There are plenty of implementations of them not by Google engineers, including a custom one in the product I work on. And developers in the Software Internals Discord are constantly in there asking questions on the road to implementing Raft or Viewstamped Replication.

[trenchpilgrim]

I believe the parent is referring to pre-raft consensus algorithms like Paxos. I recall the explanation of Paxos being a lengthy PDF while the explanation of Raft is a single webpage, mostly visual.

[eatonphil]

Could be, it was a little ambiguously worded. That said, single-decree Paxos is much simpler than Raft but I agree The Part-Time Parliament's analogy is a pain to read. But it's better if you just ignore the beginning chunk of the paper and read like the appendix; A1 The Basic Protocol being simpler to understand.

[mananaysiempre]

There’s also the side-by-side Paxos/Raft comparison in Howard & Mortier’s “Consensus on consensus”[1] paper, which is not enough to understand either by itself, but a great help if have a longer explanation you’re going through.

[1] https://dl.acm.org/doi/10.1145/3380787.3393681

[mrkeen]

Other way around.

Step 1 of Raft is for the distributed nodes to come to consensus on a fact - i.e. who the leader is.

ALL of Paxos is the distributed nodes coming to consensus on a fact.

Raft just sounds easier because its descriptions use nice-sounding prose and gloss over the details.