Plesk uses MySQL as both admin and client RDBMS. Plesk 11.5 for Linux and higher allows for MySQL alternatives (such as MariaDB or Percona Server) to be used as drop-in replacements for it. Upgrade from installations with drop-in replacements is also supported.
This guide will explain in great detail how you can replace MySQL server on a Plesk installation with MariaDB server. The guide is aimed at administrators with intermediate experience and understanding of package management for their OS. Also basic experience with services management and MySQL maintenance required.