Nagios/MySQL 错误

Question

我收到来自 Nagios 的停机警报，称主机上的 mysql 已关闭。我登录主机，在mysql error.log文件中发现如下错误。解决此问题的正确步骤是什么？

root@ubuntu:/var/log# tail -f mysql/error.log
101202 11:09:21 [ERROR] Can't open the mysql.plugin table. Please run 
                        mysql_upgrade to create it.
101202 11:09:21  InnoDB: Started; log sequence number 0 44233
101202 11:09:21 [ERROR] /usr/sbin/mysqld: Can't find file: './mysql/host.frm' 
                        (errno: 13)
101202 11:09:21 [ERROR] Fatal error: Can't open and lock privilege tables: 
                        Can't find file: './mysql/host.frm' (errno: 13)
101202 11:09:51 [Note] Plugin 'FEDERATED' is disabled.
                       /usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' 
                       (errno: 13)
101202 11:09:51 [ERROR] Can't open the mysql.plugin table. Please run 
                        mysql_upgrade to create it.
101202 11:09:52  InnoDB: Started; log sequence number 0 44233
101202 11:09:52 [ERROR] /usr/sbin/mysqld: Can't find file: './mysql/host.frm' 
                        (errno: 13)
101202 11:09:52 [ERROR] Fatal error: Can't open and lock privilege tables: 
                        Can't find file: './mysql/host.frm' (errno: 13)
101202 11:10:22 [Note] Plugin 'FEDERATED' is disabled.
                       /usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' 
                       (errno: 13)
101202 11:10:22 [ERROR] Can't open the mysql.plugin table. Please run 
                        mysql_upgrade to create it.
101202 11:10:22  InnoDB: Started; log sequence number 0 44233
101202 11:10:22 [ERROR] /usr/sbin/mysqld: Can't find file: './mysql/host.frm' 
                        (errno: 13)
101202 11:10:22 [ERROR] Fatal error: Can't open and lock privilege tables: 
                        Can't find file: './mysql/host.frm' (errno: 13)

Answer 1

找出 MySQL 找不到其表的原因。进入MySQL数据目录并查找mysql子目录（对应于mysql数据库，其中包含用户、进程、权限等内容）。也许有人删除了 mysql 数据库。也许有人用指向错误数据目录的文件覆盖了您的 my.cnf 配置文件。