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When we look at the earlier attempts to solve consensus problem in distributed systems, we encounter Raft and Paxo, are they analogous to what we see while comparing the technology behind Bitcoin vs Ethereum ?

Ref: http://ds.cs.ut.ee/courses/course-files/MartBakhoff-consensus.pdf

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No; Ethereum and Bitcoin's consensus algorithm is very different from Raft and Paxos. Ways in which they differ:

  • In both Raft and Paxos, the systems elect a leader. There is no leader in Ethereum and Bitcoin.
  • In both Raft and Paxos, all members of the cluster are trusted. In Ethereum and Bitcoin, one needs trust in only 51% of the holders of hash power.
  • The number of nodes in Ethereum and Bitcoin can fluctuate without notifying other members of the network; in Raft and Paxos, these values are predetermined. This makes it difficult to scale Raft and Paxos; furthermore, with a fixed number of nodes, one probably needs to give up security (by allowing any node to join) or node anonymity (to authenticate).

Ways in which they are the same:

  • The systems result in a consistent state.
  • A single system proposes state changes (at present, selected "at random" by mining in Ethereum and Bitcoin, and by election for Raft and Paxos).
  • Temporary forks can be formed (when there are network propagation delays or competing chains for Ethereum and Bitcoin and when there network issues for Paxos -- Raft simply stops working with less than a majority of nodes on-line).
  • The protocols for all four systems have a rule against deleting past transactions (or, rather, they only have rules for adding new ones).

Thanks to @BadrBellaj for additional points of difference.

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  • Among other points, i add that paxos and raft doesn't scale, its hard to use them in big networks like ethereum and btc but in small ones..i think it is impossible to use them in anonymous networks
    – Badr Bellaj ♦
    Aug 7, 2017 at 22:48
  • @lungj and BadrBellaj. Thanks for your insights. As per Bakhoff's paper in reference, Both Paxos and Raft differ mostly by their focus (Raft aims to provide a complete practical algorithm whereas Paxos provides the building blocks of a consensus algorithm). What I wanted to clarify is, whether this kind of "shift in focus" is analogous when we try to differentiate Bitcoin Blockchain and Ethereum Blockchain. In simple words, what Paxo is to Raft, is it in the same lines that Ethereum Blockchain is to Bitcoin Blockchain. Hope I made myself clear.
    – Mayukh Mukhopadhyay
    Aug 8, 2017 at 8:44
  • If I understand you correctly, the answer to your question is that Ethereum and Bitcoin presently use (more or less) the same consensus algorithm as each other. More generally, they are both complete practical algorithms and no longer "proofs of concept".
    – lungj
    Aug 8, 2017 at 13:00

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