警告提示：

[/usr/lib/tmpfiles.d/mdadm.conf:1] Line references path below legacy directory /var/run/, updating /var/run/mdadm → /run/mdadm; please update the tmpfiles.d/ drop-in file accordingly.
[/usr/lib/tmpfiles.d/mysql.conf:23] Line references path below legacy directory /var/run/, updating /var/run/mysqld → /run/mysqld; please update the tmpfiles.d/ drop-in file accordingly.

解决方案：

vim /usr/lib/tmpfiles.d/mdadm.conf
vim /usr/lib/tmpfiles.d/mysql.conf

然后按照提示删掉/run。