mysql-5.7.21 start error, modify database storage directory

mysql-5.7.21 start error, Permanent solution
chmod +x/etc/rc.d/rc.local
#往里面写入两条命令, which means to automatically create mysqld and modify owner permissions for boot
Ehco "Mkdir-p/var/run/mysqld
Chown-r Mysql:mysql/etc/var/mysqld
"/etc/rc.d/rc.local

#修改数据库存放目录
Systemctl Stop Mysqld #将数据库服务器停止
Mkdir-p/data/mysql/#创建目录
Chown-r Mysql:mysql/data/mysql #修改文件夹所有者
Cp-r/var/lib/mysql/ /data/mysql
Chown-r mysql:mysql/data/mysql/
Ls-l/data/mysql/
Vi/etc/my.cnf
Datadir=/data/mysql
Socket=/data/mysql/mysql.sock

Save exit
Systemctl Start mysqld
Systemctl Status Mysqld

mysql-5.7.21 start error, modify database storage directory