Consensus Algorithm (Validation & Commit Phase) Questions #consensus #raft

Robert Broeckelmann


I've been researching details of how the validation phase of the default HyperLedger Fabric consensus algorithm works. We're using the RAFT Orderer. I've got a couple of questions:
1. We've found the code (HLF 1.4.2 code base) where each peer individually (and locally) validates each transaction in a block before committing the block to the local copy of the blockchain. Does the HLF 1.4.2 peer validate the hash (DataHash field) on each block before committing the block to the local blockchain? We haven't been able to find where this happens in the code.
2. If there were a difference between the validation phase results of a block between two peers, for whatever reason, what happens? Is there some type of coordination (voting) on what the results should be for block validation between the committing peers (all peers on a channel)?
3.  The HLF Consensus Algorithm is described as a voting-based algorithm. Is that referring to the "voting" that occurs in the Endorsement Phase as to whether an endorsing peer endorses a transaction? Or, does it refer to each peer validating the "block" and "voting" on whether the block is valid?  I'm likely abusing nomenclature in at least one of those sentences:).
4. Are the answers to any of these questions different for the Kafka Orderer?

Thanks ahead of time.


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