I’m not sure, I used the MySQL defaults. Also, I needed to increase it (above 64M) because of some (very) big blobs.
Even though, I think we should focus on the error that didn’t get noticed by the back-up script. I’ve seen file system errors (i.e. not enough disk space) caused by command line actions from the back-up script, so I think the concept is already available in the script.
Can’t the backup script spot errors from the mysqldump-process? So in case there’s some kind of STDERR, it gets returned to the back-up process so that it can spot errors? And/or noticing not-0-return-value endings? I think those 2 tests should notice these kind of errors. There are more errors like this possible and they should be spotted by monitoring this I think.