MySQL databases created through Virtualmin are set sgid, presumably to track it's quota use
drws--S--- 2 mysql music 4096 Jun 6 12:46 music
Virtual domains that have reached their quota limit cause MySQL to fail to start with an error like:
Error: Write to file ./music/wp_postmeta.ibd failed at offset 0 819200
Someone didn't think their cunning plan all the way through.