Install MariaDB 10.1 - CentOS 7

cat << 'EOL' >/etc/yum.repos.d/MariaDB.repo
# MariaDB 10.1 CentOS repository list - created 2016-12-21 16:21 UTC
# http://downloads.mariadb.org/mariadb/repositories/
[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.1/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1
EOL
yum install -y MariaDB-server MariaDB-client
systemctl start mariadb.service
systemctl enable mariadb.service
/etc/init.d/mysql status

ERROR! MySQL is running but PID file could not be found

systemctl stop mariadb.service
systemctl disable mariadb.service
systemctl stop mysql.service
systemctl disable mysql.service
service mysql start
service mysql status