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  1. Percona XtraDB Cluster
  2. PXC-875

[Warning] WSREP: Unsupported protocol downgrade: incremental data collection disabled. Expect abort.

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    Details

    • Type: Bug
    • Status: Done
    • Priority: Medium
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
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      Description

      Related to https://bugs.launchpad.net/codership-mysql/+bug/1379204

      I investigated this (since I was seeing in my local MTR runs).

      To repro, run the galera.galera_suspend_slave test followed by the galera.pxc-421 test.

      The bug occurs because the suspend_slave test runs long enough to establish the protocol version and pxc-421 uses the same running servers.

      When we stop the wsrep provider, the information is not being reset, so a warning is issued because of the downgrade in capabilities.

      • Galera defaults the repl_proto_ver to -1.
      • We then request the capabilities (while the version is -1) (wsrep_view_handler_cb() in wsrep_mysqld.cc)
      • We receive the v4 capabilities (the default) with the incremental data collection bit set to 0
      • At some point the real protocol version is established (v7), so we get the v5 set of capabilities with the incremental data collection bit set to 1. (galera_capabilities() in wsrep_provider.cpp)
      • Now the PXC-421 test restarts the wsrep_provider, so galera now has a version of -1 again (but wsrep still has the incremental data collection enabled)
      • Since it's been restarted, the capabilities is requested again and since the version is -1, the incremental data collection bit is set to 0
      • This then triggers the warning message as WSREP has the bit enabled and it is now being disabled.

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            Assignee:
            kenn.takara Kenn Takara
            Reporter:
            kenn.takara Kenn Takara
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