一次非法关机导致mysql数据表损坏的实例解决

排查修复数据表的经过：

1、访问网页，提示错误，连接不到数据库。

2、启动mysql服务，卸载和关闭rpm安装的mysql服务

（昨天安装postfix好像yum安装了mysql），用netstat -anp |grep mysqld 命令查看mysql服务没有起来，用mysql -uroot -p也连接不到服务器。

3、查看错误提示：

110726 17:02:23 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. 
110726 17:02:23 [ERROR] /usr/local/mysql/libexec/mysqld: Table './mysql/host' is marked as crashed and last (automatic?) repair failed 
110726 17:02:23 [ERROR] Fatal error: Can't open and lock privilege tables: Table './mysql/host' is marked as crashed and last (automatic?) repair failed 110726 17:02:23 mysqld_safe mysqld from pid file /var/lib/mysql/localhost.localdomain.pid ended 
110726 17:24:31 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 
110726 17:24:31 [Warning] '--skip-locking' is deprecated and will be removed in a future release. Please use '--skip-external-locking' instead.
发现提示数据库表损坏。（./mysql/host）

4、修复数据库表：

cd /var/lib/mysql/mysql 
myisamchk -of host.MYI 
- recovering (with keycache) MyISAM-table 'host.MYI' 
Data records: 0 
表host.MYI修复成功。

5、再次启动服务，查看服务是否启动，登录mysql，还是不行。所以再次查看错误日志。

/usr/local/mysql/libexec/mysqld: Table './mysql/plugin' is marked as crashed and last (automatic?) repair failed 
/usr/local/mysql/libexec/mysqld: Table 'plugin' is marked as crashed and last (automatic?) repair failed 
110726 17:24:31 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. 
110726 17:24:31 [ERROR] /usr/local/mysql/libexec/mysqld: Table './mysql/user' is marked as crashed and last (automatic?) repair failed 
110726 17:24:31 [ERROR] Fatal error: Can't open and lock privilege tables: Table './mysql/user' is marked as crashed and last (automatic?) repair failed 110726 17:24:31 mysqld_safe mysqld from pid file /var/lib/mysql/localhost.localdomain.pid ended 
110726 17:27:13 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 
110726 17:27:13 [Warning] '--skip-locking' is deprecated and will be removed in a future release. Please use '--skip-external-locking' instead.

6、又发现./mysql/user表损坏。

[root@localhost mysql]# myisamchk -of user.MYI 
- recovering (with keycache) MyISAM-table 'user.MYI' 
Data records: 6

7、表修复成功，但是还是启动不了服务，继续看错误日志。

/usr/local/mysql/libexec/mysqld: Table './mysql/plugin' is marked as crashed and last (automatic?) repair failed 
/usr/local/mysql/libexec/mysqld: Table 'plugin' is marked as crashed and last (automatic?) repair failed 
110726 17:27:13 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.