[#MXS-2110] swithover fails with error Unknown error'. Query: 'FLUSH LOGS

We are testing MaxScale with a simple Master-Slave servers running MariaDB 10.1. Automatic failover works fine.

We have two servers:

server1 = INFDMYS001.example.gov.uk
server2= npedbmys001.example.gov.uk

We have successfully tested following event series:

Server1 goes down -> server2 is promoted as new Master
Server1 comes back -> server1 rejoins cluster as 'new_slave'
Server2 goes down -> server1 is promoted as new Master
Server2 comes back -> server2 rejoins cluster as 'new_slave'

[root@INFDMYS001 ~]# maxadmin list servers

Servers.

-------------------+-----------------+-------+-------------+--------------------

Server             | Address         | Port  | Connections | Status

-------------------+-----------------+-------+-------------+--------------------

server1            | INFDMYS001.example.gov.uk |  3306 |           0 | Master, Running

server2            | npedbmys001.example.gov.uk |  3306 |           0 | Slave, Running

-------------------+-----------------+-------+-------------+--------------------

But switchover does not work:

# maxadmin call command mariadbmon switchover ReplMonitor server2 server1

2018-10-24 08:56:14   notice : (15) [mariadbmon] Stopped the monitor ReplMonitor for the duration of switchover.

2018-10-24 08:56:14   notice : (15) [mariadbmon] Demoting server 'server1'.

2018-10-24 08:56:14   error  : (15) [mariadbmon] Demotion failed due to a query error: 'Unknown error'. Query: 'FLUSH LOGS;'.

2018-10-24 08:56:14   error  : (15) [mariadbmon] Switchover server1 -> server2 failed, failover has been disabled..

    "errors": [

            "detail": "Demotion failed due to a query error: 'Unknown error'. Query: 'FLUSH LOGS;'."

},

            "detail": "Switchover server1 -> server2 failed, failover has been disabled.."

Monitor user has all required privileges:

MariaDB [(none)]> show grants for maxscale@'%';

+------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| Grants for maxscale@%                                                                                                                                                  |

+------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

| GRANT RELOAD, SHOW DATABASES, SUPER, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'maxscale'@'%' IDENTIFIED BY PASSWORD '*53E5D0C7885BD540911663B04133F20C94AD4306' |

| GRANT SELECT ON `mysql`.* TO 'maxscale'@'%'                                                                                                                            |

+------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

2 rows in set (0.00 sec)

I have attached maxscale log and config files.

[MXS-2110] swithover fails with error Unknown error'. Query: 'FLUSH LOGS Created: 2018-10-24 Updated: 2019-01-23 Resolved: 2019-01-23
Status:	Closed
Project:	MariaDB MaxScale
Component/s:	failover
Affects Version/s:	2.2.4
Fix Version/s:	2.2.4

[MXS-2110] swithover fails with error Unknown error'. Query: 'FLUSH LOGS Created: 2018-10-24 Updated: 2019-01-23 Resolved: 2019-01-23