It seems MariaDB changed the service name for CentOS 7 yum packages of MariaDB 10.1.9 ? prior it was service name = mysql but now mariadb ?
However, both servcie names exist but for mysql service name you get incorrectly reported error that mysql isn't running. CentOS 7 usually can use both service or systemctl versions together.
these 3 work
but this doesn't
but seems only systemctl mysql service name works like it's mariadb service name counterpart
CentOS 7.1 64bit