$ systemctl stop mysqld
$ cp -rp /var/lib/mysql /var/lib/mysql_backup
cp -rp /data/mysql/data /data/mysql/data_backup
$ vim /etc/my.cnf
[mysqld]
innodb_log_file_size = 指定大小 # 单位字节
$ rm -f /var/lib/mysql/ib_logfile*
$ systemctl start mysqld
$ SHOW VARIABLES LIKE 'innodb_log_file_size';