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If you have a Galera Cluster in place, you should also monitor the health of the cluster and each node.
We also recommend to observe the Backup Process of MySQL. You could check the file size of the backup and the timestamp.
Appendix
Some monitoring systems are not able to check all these components directly. You can use workarounds like Powershell and Windows Task Scheduler to create a monitoring-text-file. Then you can check this text file content (please do not forget to check the age of the text-file with the monitoring - this way you make sure, the values are up to date). If you need assistance with that, we are happy to help you.
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