We've been running a large RDS instance in production for over year without a single moment of downtime. Recently, with a bigger budget and higher stakes, we decided to convert it to a multi-AZ instance, to improve reliability and redundancy of our data.
Since then (about two weeks ago), we've had two serious failures of our instance which required rebooting. There is nothing in the 'recent DB events'. There were two DB connection spikes recorded in cloudwatch that occurred at the same time as the failures.
What's going on?