问题描述：
centos 安装MySQL
$yum install mysql-server
安装之后执行命令mysql
报错：
查看mysql的启动日志：
[ERROR] InnoDB: auto-extending data file ./ibdata1 is of a different size 640 pages (rounded down to MB) than specified in the .cnf file: initial 768 pages, max 0 (relevant if non-zero) pages!
2016-02-22 23:02:55 29830 [ERROR] InnoDB: Could not open or create the system tablespace. If you tried to add new data files to the system tablespace, and it failed here, you should now edit innodb_data_file_path in my.cnf back to what it was, and remove the new ibdata files InnoDB created in this failed attempt. InnoDB only wrote those files full of zeros, but did not yet use them in any way. But be careful: do not remove old data files which contain your precious data!
2016-02-22 23:02:55 29830 [ERROR] Plugin 'InnoDB' init function returned error.
2016-02-22 23:02:55 29830 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2016-02-22 23:02:55 29830 [ERROR] Unknown/unsupported storage engine: InnoDB
2016-02-22 23:02:55 29830 [ERROR] Aborting
解决方法：
执行删除命令：rm -rf /var/lib/mysql/ib*
删除：ibdata1、ib_logfile0、ib_logfile1文件
重新启动：service mysqld start