I used to work in the orbit of a distinguished eng at AWS who was famous for saying something to the effect of, "At the bottom of any scaled distributed system is either Paxos, or a bug."
I was fairly junior at the time, and Raft seemed much more approachable, but after really forcing myself to read and understand the Paxos paper, I see what he meant. I am pretty sure most of the love for Raft was that the original whitepaper was just a better presentation. The actual Paxos algorithm is quite simple.
If you go into Raft already having mastered Paxos (as this DE was doing), it's clear that Raft is basically isomorphic to a special case of Paxos.
This paper argues basically argues that raft has a different leadership election mechanism than paxos, but that if you tweak some terminology, and make a few relatively reasonable implementation choices for paxos they are otherwise pretty equivalent.
It even gives a raft style single page description of paxos (using raft style terminology), and shows how little it differs from the equivalent single page summary of raft.
The main implementation choices they use are: - combined roles into a single server role - enforce that log messages are decided in sequence (largely to avoid the having to specify the behavior of newly elected leader to propose operations for the gaps (possibly no-ops)) - numeric ballot number, rather than lexicographical pair (but this changes nothing except making the summary slightly easier to express)
We should start considering CRDT/OT/VCS/Diffsync approaches to distributed systems as well. They present a very nice alternative approach: whereas PAXOS/RAFT implement a consistent "distributed state machine", a CRDT, OT, VCS, or Diffsync system implements consistent "distributed state", upon which one can build a machine as a function of the state.
This latter approach is actually simpler, IMO, because it encapsulates all the challenge of distributed consistency within a smaller subset of the problem — state synchronization. This makes it more generally re-usable. When you create a system, you can just use an off-the-shelf library & algorithm to synchronize your data over a network, and then write synchronous functions on top of that to represent the system you want, however you want, without having to understand PAXOS/RAFT.
Paxos is complicated, but it’s well studied and proven.
"There are three types of consistent distributed systems: paxos, broken protocols, and single points of failures."
knowing who said this allows readers to be able to look up more of the (unfortunately scant) content publicly available from him.
It's almost more impressive that people know who it is without saying the name.
After reading the blogs about how good Erlang's concurrency model is and how we just just made a super implementation of it in XXX I have been led to formulate Virding's First Rule of Programming:
Any sufficiently complicated concurrent program in another language contains an ad hoc informally-specified bug-ridden slow implementation of half of Erlang.
This is, of course, a mild travesty of Greenspun (*) but I think it is fundamental enough to be my first rule, not the tenth.
[0] http://erlang.org/pipermail/erlang-questions/2008-January/03...