Core Server
  1. Core Server
  2. SERVER-9730

Asymmetrical network partition can cause the election of two PRIMARY nodes

    Details

    • Type: Bug Bug
    • Status: Closed Closed
    • Priority: Critical - P2 Critical - P2
    • Resolution: Fixed
    • Affects Version/s: 2.2.4, 2.4.3, 2.5.0
    • Fix Version/s: 2.2.5, 2.4.4, 2.5.1
    • Component/s: Replication/Pairing
    • Labels:
      None
    • Backport:
      Done
    • Operating System:
      ALL
    • Bug Type:
      Logical
    • # Replies:
      16
    • Last comment by Customer:
      true

      Description

      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.

        Issue Links

          Activity

          Hide
          Volodymyr Gren
          added a comment -

          So if I correctly understood Eric - we cant face this bug in environment when there is arbiter, primary and secondary, right?

          just environment with primary and two secondaries could be affected?

          Show
          Volodymyr Gren
          added a comment - So if I correctly understood Eric - we cant face this bug in environment when there is arbiter, primary and secondary, right? just environment with primary and two secondaries could be affected?
          Hide
          Eric Milkie
          added a comment -

          An environment where there is an arbiter, primary, and secondary is not affected by this bug.

          Show
          Eric Milkie
          added a comment - An environment where there is an arbiter, primary, and secondary is not affected by this bug.
          Show
          Volodymyr Gren
          added a comment - So looks William was not right in his statement https://jira.mongodb.org/browse/SERVER-9730?focusedCommentId=383129&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-383129
          Hide
          William Zola
          added a comment -

          Volodymyr Gren – You're correct: I was mistaken.

          Show
          William Zola
          added a comment - Volodymyr Gren – You're correct: I was mistaken.
          Hide
          Volodymyr Gren
          added a comment -

          thanks, now it's super clear

          Show
          Volodymyr Gren
          added a comment - thanks, now it's super clear

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              Dates

              • Created:
                Updated:
                Resolved:
                Days since reply:
                39 weeks, 6 days ago
                Date of 1st Reply: