现象： 
centos服务器异常断电MySQL启动异常启动Mysql时报错：mysqld_safe mysqld from pid file /usr/local/mysql/Linux.pid end 
但是打开日志文件 查看

InnoDB: Completed initialization of buffer pool 
InnoDB: Error: log file ./ib_logfile0 is of different size 50331648 bytes 
InnoDB: than specified in the .cnf file 5242880 bytes! 
160603 
[ERROR] Plugin ‘InnoDB’ init function returned error. 
160603 
14:06:15 [ERROR] Plugin ‘InnoDB’ registration as a STORAGE ENGINE failed. 
160603 
14:06:15 [ERROR] Unknown/unsupported storage engine: InnoDB 
160603 14:06:15 [ERROR] Aborting

处理方案：

1、存储引擎错误 
Unknown/unsupported storage engine: InnoDB 
2、检查一下配置文件中关于innodb的参数，如果有skip-innodb注释掉 
3、如果重新设置了innodb_log_file_size之类的， 
4、需?删除几个rm -rf ib_logfile，然后重启数据库