表数据文件损坏导致数据库无法启动

今天一个研发数据库突然断电后，数据库无法启动，原因是其中一个表文件损坏导致，下面是问题处理过程
2015-01-26 14:18:05 4122 [Note] InnoDB: Database was not shutdown normally!
2015-01-26 14:18:05 4122 [Note] InnoDB: Starting crash recovery.
2015-01-26 14:18:05 4122 [Note] InnoDB: Reading tablespace information from the .ibd files...
2015-01-26 14:18:05 4122 [ERROR] InnoDB: Attempted to open a previously opened tablespace. Previous tablespace dev/tb_test uses spac
e ID: 1 at filepath: ./dev/tb_test.ibd. Cannot open tablespace mysql/innodb_table_stats which uses space ID: 1 at filepath: ./mysql/
innodb_table_stats.ibd
2015-01-26 14:18:05 2ad861898590  InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: If you are installing InnoDB, remember that you must create
InnoDB: directories yourself, InnoDB does not create them.
InnoDB: Error: could not open single-table tablespace file ./mysql/innodb_table_stats.ibd
InnoDB: We do not continue the crash recovery, because the table may becomeInnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.
150126 14:18:06 mysqld_safe mysqld from pid file /home/mysql/mysql_app/dbdata/host01.pid ended

1.在my.cnf中添加如下参数
在[mysqld]组中加入：
innodb_force_recovery=6

innodb_force_recovery参数解释：
innodb_force_recovery影响整个InnoDB存储引擎的恢复状况，默认值为0，表示当需要恢复时执行所有的恢复操作。
当不能进行有效的恢复操作时，mysql有可能无法启动，并记录下错误日志。

innodb_force_recovery可以设置为1-6,大的数字包含前面所有数字的影响。
当设置参数值大于0后，可以对表进行select,create,drop操作,但insert,update或者delete这类操作是不允许的。
1(SRV_FORCE_IGNORE_CORRUPT):忽略检查到的corrupt页
2(SRV_FORCE_NO_BACKGROUND):阻止主线程的运行，如主线程需要执行full purge操作，会导致crash
 3(SRV_FORCE_NO_TRX_UNDO):不执行事务回滚操作。
4(SRV_FORCE_NO_IBUF_MERGE):不执行插入缓冲的合并操作。
5(SRV_FORCE_NO_UNDO_LOG_SCAN):不查看重做日志，InnoDB存储引擎会将未提交的事务视为已提交。
6(SRV_FORCE_NO_LOG_REDO):不执行前滚的操作。

2.备份数据库
$mysqldump -h 192.168.56.111 -uroot -p dev > /home/mysql/dev.sql

3.删除数据库
$mysql -h 192.168.56.111 -uroot -p
mysql> drop database dev;
ERROR 1051 (42S02): Unknown table 'dev.tb_test'

物理删除tb_test对应的frm和ibd文件

mysql> drop database dev;
Query OK, 0 rows affected (0.00 sec)

4.创建数据库
mysql> create database dev;
Query OK, 1 row affected (0.03 sec)

5.去掉参数innodb_force_recovery
将之前设置的参数去掉后，重新启动数据库
##innodb_force_recovery=6

6.导入数据
[mysql@host01 dev]$ mysql -h 192.168.56.111 -uroot -pmysql dev Warning: Using a password on the command line interface can be insecure.
ERROR 1050 (42S01) at line 25: Table '`dev`.`tb_test`' already exists

提示表已经存在，这是因为将innodb_force_recovery参数去掉后，数据库会进行回滚操作，会生成相应的ibd文件，所有需要将该文件删除掉.
删除后重新导入
[mysql@host01 dev]$ mysql -h 192.168.56.111 -uroot -pmysql dev
-- The End --