Error reported in MySQL: Solution of Can 't find file:'. and mysql and plugin. frm '

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Recently, I found a problem in my work. This problem is that the disk of MySQL is full. The database directory data is moved to the/data3 directory, and the corresponding datadir directory is modified in the/etc/my.cnf, and the authority is also given, but service mysql start; When reporting errors, the following words are not much to say, let's take a look at the detailed solutions.

error log is shown as follows:

2017-09-15 16:01:01 2420 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
2017-09-15 16:01:01 2420 [Note] Plugin 'FEDERATED' is disabled.
^G/usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13 - Permission denied)
2017-09-15 16:01:01 2420 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
2017-09-15 16:01:01 2420 [Note] InnoDB: Using atomics to ref count buffer pool pages
2017-09-15 16:01:01 2420 [Note] InnoDB: The InnoDB memory heap is disabled
2017-09-15 16:01:01 2420 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2017-09-15 16:01:01 2420 [Note] InnoDB: Memory barrier is not used
2017-09-15 16:01:01 2420 [Note] InnoDB: Compressed tables use zlib 1.2.8
2017-09-15 16:01:01 2420 [Note] InnoDB: Using Linux native AIO
2017-09-15 16:01:01 2420 [Note] InnoDB: Using CPU crc32 instructions
2017-09-15 16:01:01 2420 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2017-09-15 16:01:02 2420 [Note] InnoDB: Completed initialization of buffer pool
2017-09-15 16:01:02 2420 [ERROR] InnoDB: ./ibdata1 can't be opened in read-write mode
2017-09-15 16:01:02 2420 [ERROR] InnoDB: The system tablespace must be writable!
2017-09-15 16:01:02 2420 [ERROR] Plugin 'InnoDB' init function returned error.
2017-09-15 16:01:02 2420 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2017-09-15 16:01:02 2420 [ERROR] Unknown/unsupported storage engine: InnoDB
2017-09-15 16:01:02 2420 [ERROR] Aborting

To check plugin. frm permissions first, frm is MySQL table structure definition file, usually frm file will not be damaged, but if frm file is damaged in special circumstances, don't give up hope. When repairing MyISAM and InnoDB tables, MySQL service will first call frm file, so we can only repair frm file for later data recovery.

Then we found that plugin. frm has permission and is also the owner of mysql:

root@hutaojie-1-pdd-sh:/data1/mysql/mysql# ll plugin.*
-rwxrwxrwx 1 mysql mysql 8586 Mar 6 2016 plugin.frm*
-rwxrwx--x 1 mysql mysql 116 Mar 6 2016 plugin.MYD*
-rwxrwx--x 1 mysql mysql 2048 Mar 6 2016 plugin.MYI*
root@hutaojie-1-pdd-sh:/data1/mysql/mysql#

After google, it was found that the original problem lies in os. When mysql of ubatu is installed through yum or rpm, a file/etc/apparmor. d/usr. sbin. mysqld will be built. If the data directory is not in it, an error will be reported.

/usr/sbin/mysqld: Can't find file:  ' ./mysql/plugin.frm' (errno: 13 - Permission denied)

Solution

So the solution is to add a new datadir directory to it.

root@huayuan:/var/lib# vim /etc/apparmor.d/usr.sbin.mysqld 

# vim:syntax=apparmor
# Last Modified: Tue Jun 19 17:37:30 2007
#include <tunables/global>

/usr/sbin/mysqld {
 #include <abstractions/base>
 #include <abstractions/nameservice>
 #include <abstractions/user-tmp>
 #include <abstractions/mysql>
 #include <abstractions/winbind>

 capability dac_override,
 capability sys_resource,
 capability setgid,
 capability setuid,

 network tcp,

 /run/mysqld/mysqld.pid rw,
 /run/mysqld/mysqld.sock w,

 /sys/devices/system/cpu/ r,
 #......... There is a new one in it datadir Directory, write 2 OK, 1 Row r , 1 Row rwk . 
 /data3/mysql/ r,
 /data3/mysql/** rwk,
 # Site-specific additions and overrides. See local/README for details.
 #include <local/usr.sbin.mysqld>
}

Then restart the mysql instance, ok, and the problem is solved.

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