解决方法：
systemctl daemon-reload
正常重启MariaDB
systemctl restart mysql
即可。其他服务出现类似的情况，也可以使用systemctl daemon-reload来解决。
本文出自 “boyhack” 博客，请务必保留此出处http://461205160.blog.51cto.com/274918/1856836
Warning: Unit file of mysql.service changed on disk, 'systemctl daemon-reload' recommended.
标签：warning: unit file of mysql.service changed on disk 'systemctl daemon-reload' recommended.