Plugin 'InnoDB' registration as a STORAGE ENGINE failed.

一个编译好的mysql5.5, 运行时比较慢！
我帮其调整参数后，然后启动配置文件
结果不认得innodb存储引擎了！

mysql> show engines;
+--------------------+---------+-----------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+-----------------------------------------------------------+--------------+------+------------+
| MyISAM | DEFAULT | MyISAM storage engine | NO | NO | NO |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
+--------------------+---------+-----------------------------------------------------------+--------------+------+------------+
5 rows in set (0.00 sec)

mysql>

显然没有innodb存储引擎了！
在后台抛出错误：
20620 19:01:48 mysqld_safe Starting mysqld daemon with databases from /home/mysqldb/var
120620 19:01:50 InnoDB: The InnoDB memory heap is disabled
120620 19:01:50 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
120620 19:01:50 InnoDB: Compressed tables use zlib 1.2.3
120620 19:01:50 InnoDB: Initializing buffer pool, size = 512.0M
120620 19:01:50 InnoDB: Completed initialization of buffer pool
InnoDB: Error: log file ./ib_logfile0 is of different size 0 134217728 bytes
InnoDB: than specified in the .cnf file 0 268435456 bytes!
120620 19:01:50 [ERROR] Plugin 'InnoDB' init function returned error.
120620 19:01:50 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
120620 19:01:50 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
120620 19:01:50 [Note]   - '0.0.0.0' resolves to '0.0.0.0';
120620 19:01:50 [Note] Server socket created on IP: '0.0.0.0'.
120620 19:01:51 [Note] Event Scheduler: Loaded 0 events
120620 19:01:51 [Note] /home/mysql/mysql/bin/mysqld: ready for connections.
Version: '5.5.25-log'  socket: '/tmp/mysql.sock'  port: 3306  Source distribution
故障原因：我修改了my.cnf中的
innodb_log_file_size=256M 原来的大小为128M
造成日志文件大小不一致，从而不能启动innodb存储引擎（我在my.cnf中设置myisam为默认的存储引擎）
故mysql还是可以启动，但就是不能识别innodb存储引擎！
解决方法：
先关闭mysql
删除ib_logfile0 和 ib_logfile1
重新启动即可！