https://www.databasejournal.com/features/mysql/calculating-mysql-database-table-and-column-sizes.html
https://www.digitalocean.com/community/tutorials/how-to-create-hot-backups-of-mysql-databases-with-percona-xtrabackup-on-ubuntu-14-04
https://mariadb.com/resources/blog/getting-started-with-mariadb-galera-and-mariadb-maxscale-on-centos/