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simbo1905’s ramblings about computers

Tag: FPaxos

One More Frown Please? (UPaxos Quorum Overlaps)

There was some discussion around UPaxos safety on a gist where Dave Turner was kind enough to clarify a confusion of mine. I had said that we needed an overlap between prepare quorums to avoid a split-brain. This was incorrect and I am greatful for Dave for correcting my misunderstanding. Yet there was something about not having that overlap that was bugging me… This morning I had an “Aha!” moment: if it exists then Trex will perform an optimisation. Yet in Trex this overlap is not enforced.

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UPaxos: Unbounded Paxos Reconfigurations

The year 2016 turned out to be a bumper year for pragmatic Paxos discoveries. Hot on the heels of the FPaxos discovery of more flexible quorums comes Unbounded Pipelining in Dynamically Reconfigurable Paxos Clusters or “UPaxos”. This uses overlapping quorums between consecutive cluster configurations, and a leader “casting vote”, to enable cluster reconfigurations in a non-stop manner even when reconfiguration messages are lost. Read the rest of this entry »