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  1. Core Server
  2. SERVER-9730

Asymmetrical network partition can cause the election of two PRIMARY nodes

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    • Type: Icon: Bug Bug
    • Resolution: Done
    • Priority: Icon: Critical - P2 Critical - P2
    • 2.2.5, 2.4.4, 2.5.1
    • Affects Version/s: 2.2.4, 2.4.3, 2.5.0
    • Component/s: Replication
    • Labels:
      None
    • ALL

      Consider a replica set with three nodes: A, B, C. 'A' is PRIMARY, 'B' and 'C' are SECONDARY.

      If there is a network partition between 'A' and 'C', then:

      • A is still PRIMARY because it can see a majority of the set
      • C will start an election trying to become PRIMARY
        • It can see a majority of the set
        • It cannot see a primary

      If, for whatever reason, 'B' allows 'C' to become PRIMARY, then the set will have two PRIMARY nodes until one of them is stepped down.

            Assignee:
            milkie@mongodb.com Eric Milkie
            Reporter:
            william.zola@10gen.com William Zola
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              Created:
              Updated:
              Resolved: