There has been a lot of rumour recently, about RedHat switching from MySQL to MariaDB in RHEL 7. Be careful with these rumours. So far, I have not yet found any official and authoritative statement by RedHat, pointing in this direction. Instead, I've found claims that this is still undecided: http://paritynews.com/software/item/1134-red-hat-denies-ditching-mysql-move-to-mariadb