random failover on idle dbs

Lénárd Pásztor

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Apr 23, 2024, 4:57:07 AM4/23/24

to MariaDB MaxScale

Hi,

I'm testing mariadb-operator 0.27. Created a mariadb 11.3.2 replication and running a maxscale 23.08.5 instance on top of it.

The dbs are empty, not in use, the network is stable between the nodes, but I see random failovers on the logs. Here is some example:

maxscale:

2024-04-22 21:30:19 error : Monitor was unable to connect to server example-mariadb-1[example-mariadb-1.example-mariadb-internal.example-mariadb.svc.k8s.prod.examplesystem:3306] : 'Host '10.101.9.176' is not allowed to connect to this MariaDB server'
2024-04-22 21:30:19 notice : Server changed state: example-mariadb-1[example-mariadb-1.example-mariadb-internal.example-mariadb.svc.k8s.prod.examplesystem:3306]: slave_down. [Slave, Running] -> [Down]
2024-04-22 21:30:19 notice : Server changed state: example-mariadb-1[example-mariadb-1.example-mariadb-internal.example-mariadb.svc.k8s.prod.examplesystem:3306]: slave_up. [Down] -> [Slave, Running]

on the maraidb-1 log:

2024-04-22T23:30:19+02:00 2024-04-22 21:30:19 41689 [Warning] Aborted connection 41689 to db: 'unconnected' user: 'unauthenticated' host: '10.101.9.176' (This connection closed normally without authentication)

What can be the problem? Hogy can I debug it? Thanks!

uaxia-mariadb-1[nuaxia-mariadb-1.nuaxia-mariadb-internal.nuaxia-mariadb.svc.k8s.prod.nuaxiasystem:3306]: slave_up. [Down] -> [Slave, Running]

Markus Mäkelä

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Apr 23, 2024, 5:10:32 AM4/23/24

to maxs...@googlegroups.com

Hi,

The failure you see is not what is usually referred to as a "failover" in MaxScale and it is simply a state change. The reason for this state change is in the error message: Host '10.101.9.176' is not allowed to connect to this MariaDB server. This means that the MariaDB instance refused to allow access from the host 10.101.9.176 where MaxScale was connecting from and the monitor deemed the node unusable and marked the node as Down. Later on, it seems that the host was allowed to connect which then explains why it went back to the Slave, Running state.

Markus

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Markus Mäkelä, Senior Software Engineer
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