今天重启 mysql 服务器的时候，遭遇了下面的错误：
180316 10:43:44 mysqld_safe mysqld from pid file /mysqldata/mysql_data/centos.pid ended
180316 10:45:35 mysqld_safe Starting mysqld daemon with databases from /mysqldata/mysql_data
/usr/libexec/mysqld: Character set 'utf8mb4' is not a compiled character set and is not specified in the '/
usr/share/mysql/charsets/Index.xml' file
180316 10:45:35 [ERROR] Aborting检查配置文件（ /etc/my.cnf ） ，发现了以下参数：
character_set_server=utf8mb4
为了先暂时规避这个问题，将改参数注释掉了，之后正常启动