|OS type and version:||Ubuntu 18.04.6 LTS|
|Related products version:||MySQL 5.7.36|
I found out that the Virtualmin back-up never showed any warnings/errors because of an error concerning too large packets while exporting the database using mysqldump. (something like “Error 2020: Got packet bigger than ‘max_allowed_packet’ bytes when dumping table”)
The database back-up was included in the back-up files Virtualmin made, but was approx 500 MB (gzipped). No errors appeared in the back-up log.
After increasing the max_allowed_packet in the [mysqldump] section in mysql-config the back-up file increased to 1 GB+ (gzipped again of course) because it could now complete the dump.
Conclusion: some of the mysqldump data missed in the previous back-ups. This didn’t cause any errors even though mysqldump should return some.
Possibly very dangerous because I didn’t know my back-ups were incomplete.