4 ms·
Thanks, great to hear you enjoyed it! The round robin "view change" in VSR is still consensus, and uses quorums to do fault isolation of the old primary, and t
by jorangreef 3y ago
Thanks, great to hear you enjoyed it!
The round robin "view change" in VSR is still consensus, and uses quorums to do fault isolation of the old primary, and to preserve the intersection property, to ensure that the committed log survives into the new view.
What's cool about VSR's consensus though, is that the dice is also preloaded, ahead of time, so that there's more information baked into the protocol than with Raft or MultiPaxos, which means that you can neatly sidestep their dueling leader problem, or the latency padding that is often added to mitigate it.
You can read more about VSR's intuitive view change consensus here: http://pmg.csail.mit.edu/papers/vr-revisited.pdf http://pmg.csail.mit.edu/papers/vr-revisited.pdf
The round robin view chance can also make VSR (slightly) more resilient to weird network faults, like you describe. For example, variants of VSR using stable storage as hinted at by the '12 paper, are in fact able to survive most of the OmniPaxos liveness scenarios (we submitted some errata to the paper's authors for this).
We haven't yet explored visualizing asymmetric connectivity in SimTigerBeetle (we tried to start with the big things!), however we recently wrote about how we test for this in our VOPR simulator here: https://tigerbeetle.com/blog/2023-07-06-simulation-testing-for-liveness/ https://tigerbeetle.com/blog/2023-07-06-simulation-testing-f...
- schmichael 3y agoThanks for the details. A coworker pointed me at Heidi Howard (of Flexible Paxos, etc) and Diego Ongaro (Raft) discussing this very question! https://groups.google.com/g/raft-dev/c/cBNLTZT2q8o?pli=1 https://groups.google.com/g/raft-dev/c/cBNLTZT2q8o?pli=1
- jorangreef 3y agoYes, I think Heidi Howard gets it spot on there, in that the main difference is the view change. (TB implements Flexible Paxos and we're fans of Heidi Howard's work!)