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 ?
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.