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  1. MariaDB MaxScale
  2. MXS-5955

Wrong master selected after restart

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Critical
    • Resolution: Not a Bug
    • 22.08.18, 23.02.15, 23.08.11, 24.02.7, 25.01.4, 25.10.0
    • N/A
    • mariadbmon
    • None
    • MXS-SPRINT-244, MXS-SPRINT-245, MXS-SPRINT-246, MXS-SPRINT-247, MXS-SPRINT-248

    Description

      Original issue:
      If cooperative monitoring is used with two MaxScales and three MariaDB servers, after a restart of one MaxScale sometimes the wrong server is selected as the master.

      Comments:
      I don't see how two MaxScales could persist with different master servers. There is a possible issue with the monitor journal, in that if the persisted journal states are loaded and taken into use before a monitor tick. Usually this is not an issue, as the old master would have read_only on when the downed MaxScale comes back. If, however, the old master and MaxScale come back at the exact same moment, then for a split second, the restored MaxScale can have the wrong master. The solution to this is to ignore server roles read from the monitor journal until the monitor confirms the roles by performing a real monitor tick. However, it is unknown if this is what happened in the support case.

      Attachments

        Issue Links

          blocks

          New Feature - A new feature of the product, which has yet to be developed. MXS-5064 Configure server correctly after crash

          • Major - Major loss of function.
          • Needs Feedback
          causes

          New Feature - A new feature of the product, which has yet to be developed. MDEV-34878 Semisync recovery mode

          • Critical - Crashes, loss of data, severe memory leak.
          • Needs Feedback

          Task - A task that needs to be done. MXS-6034 Document case MXS-5955

          • Major - Major loss of function.
          • Open
          relates to

          New Feature - A new feature of the product, which has yet to be developed. MDEV-38202 add init_rpl_role in output of "show variables"

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MXS-6032 Add robust semisync replication setup tutorial to MaxScale documentation

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Closed

          Activity

            People

              esa.korhonen Esa Korhonen
              markus makela markus makela
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              Dates

                Created:
                Updated:
                Resolved:

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