无法启动 mysql：
130408 11:31:22 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
/usr/libexec/mysqld: Table 'plugin' is read only
130408 11:31:22 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
130408 11:31:22 InnoDB: Initializing buffer pool, size = 8.0M
130408 11:31:22 InnoDB: Completed initialization of buffer pool
130408 11:31:23 InnoDB: Started; log sequence number 0 19514977
130408 11:31:23 [ERROR] Can't start server : Bind on unix socket: Permission denied
130408 11:31:23 [ERROR] Do you already have another mysqld …