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  1. MariaDB MaxScale
  2. MXS-656

after upgrade from 1.3 to 1.4, selecting master isn't working as expected

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.4.0, 1.4.1
    • Fix Version/s: 1.4.2
    • Component/s: galeramon
    • Labels:
      None
    • Environment:
      CentOS release 6.7 (Final)
      kernel: 2.6.32-573.18.1.el6.x86_64
      Galera Cluster / MariaDB: 5.5.46-MariaDB-wsrep MariaDB Server, wsrep_25.12.r4f81026

      Description

      We have 12 MaxScale (version 1.3.0) servers running at the moment, behind HAproxy and connected to a Galera Cluster of 4 nodes (1 master, 3 slaves)

      I've put 1 server in maintenance, so I could try to update MaxScale to 1.4.1.

      Situation before updating (and running 1.3.0):

      # maxadmin -pmariadb list servers
      Servers.
      -------------------+-----------------+-------+-------------+--------------------
      Server             | Address         | Port  | Connections | Status
      -------------------+-----------------+-------+-------------+--------------------
      db-03          | 192.168.120.74  |  3306 |          22 | Master, Synced, Running
      db-04          | 192.168.120.95  |  3306 |          23 | Slave, Synced, Running
      db-05          | 192.168.120.96  |  3306 |          22 | Slave, Synced, Running
      db-06          | 192.168.120.97  |  3306 |          23 | Slave, Synced, Running
      -------------------+-----------------+-------+-------------+--------------------
      

      After updating (running 1.4.1)

      # maxadmin -pmariadb list servers
      Servers.
      -------------------+-----------------+-------+-------------+--------------------
      Server             | Address         | Port  | Connections | Status
      -------------------+-----------------+-------+-------------+--------------------
      db-03          | 192.168.120.74  |  3306 |           1 | Slave, Synced, Running
      db-04          | 192.168.120.95  |  3306 |           1 | Slave, Synced, Running
      db-05          | 192.168.120.96  |  3306 |           1 | Slave, Synced, Running
      db-06          | 192.168.120.97  |  3306 |           1 | Master, Synced, Running
      -------------------+-----------------+-------+-------------+--------------------
      

      Whatever we do, we can't get db-03 to be Master again. It will always change back to db-06.
      db-03 has the lowest wsrep_local_index, so it should be elected as Master, right?

      We've noticed some difference in the "Node Id" from "show servers" output. On 1.3.0, the Node Id = 0 and on 1.4.1 the Node Id = -1

      On 1.3.0:

      # maxadmin -pmariadb show servers | egrep 'Id|Server '
      Server 0x25903f0 (db-03)
              Server Version:                 5.5.45-MariaDB-wsrep
              Node Id:                     0
              Master Id:                   -1
      Server 0x25902b0 (db-04)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     3
              Master Id:                   -1
      Server 0x2590190 (db-05)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     2
              Master Id:                   -1
      Server 0x258ffc0 (db-06)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     1
              Master Id:                   -1
      

      On 1.4.1:

      # maxadmin -pmariadb show servers | egrep 'Id|Server '
      Server 0x87efe0 (db-03)
              Server Version:                 5.5.45-MariaDB-wsrep
              Node Id:                     -1
              Master Id:                   -1
      Server 0x87eea0 (db-04)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     3
              Master Id:                   -1
      Server 0x87ed60 (db-05)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     2
              Master Id:                   -1
      Server 0x87eb70 (db-06)
              Server Version:                 5.5.46-MariaDB-wsrep
              Node Id:                     1
              Master Id:                   -1
      

      The logfile shows some errors:

      2016-04-01 09:50:36   error  : Couldn't find suitable Master from 4 candidates.
      2016-04-01 09:50:36   error  : Failed to create new router session for service 'Splitter Service'. See previous errors for more details.
      

      When we downgrade back to 1.3.0, server db-03 is Master again.

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            Assignee:
            markus makela markus makela
            Reporter:
            wschaft Wesley Schaft
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              Dates

              Created:
              Updated:
              Resolved: