發現問題
最近在工作中發現了一個問題，這個問題就是MySQL的磁盤滿了，將數據庫目錄data移動到/data3目錄，/etc/my.cnf里面也修改了相應的datadir目錄，權限也賦予了，但是service mysql start;的時候報錯，下面話不多說了，來一起看看詳細的解決方法吧。
error log顯示如下：
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
去先檢查plugin.frm權限，frm是MySQL表結構定義文件，通常frm文件是不會損壞的，但是如果出現特殊情況出現frm文件損壞也不要放棄希望，當修復MyISAM和InnoDB表時，MySQL服務會首先去調用frm文件，所以我們只能通過修復frm文件進行后面的數據恢復。
然后我們發現plugin.frm有權限，也是mysql屬主：
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#
google之后發現，原來問題在os這里，ubatu的mysql通過yum安裝或者rpm安裝的時候，會建一個/etc/apparmor.d/usr.sbin.mysqld 文件，如果數據目錄不在這里面，則會報錯，
/usr/sbin/mysqld: Can't find file: ‘./mysql/plugin.frm' (errno: 13 - Permission denied)
解決方法
所以解決辦法是在里面加上新的datadir目錄。
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,
#.........這里面寫新的datadir目錄，寫2行，一行r，一行rwk。
/data3/mysql/ r,
/data3/mysql/** rwk,
# Site-specific additions and overrides. See local/README for details.
#include local/usr.sbin.mysqld>
}
然后重啟mysql實例，ok，問題解決。
總結
以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，如果有疑問大家可以留言交流，謝謝大家對腳本之家的支持。
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