爲何mysqld啓動報錯

在一臺ubuntu測試機器上啓動一個mysql實例，原本應該是一件很簡單的事情，

啓動的時候卻報錯了：

 

mysqld_safe --defaults-file=/etc/mysql/my3307.cnf
160218 15:45:13 mysqld_safe Can't log to error log and syslog at the same time.  Remove all --log-error configuration options for --syslog to take effect.
160218 15:45:13 mysqld_safe Logging to '/var/log/mysql/error3307.log'.
160218 15:45:13 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql3307
160218 15:45:15 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld3307.pid ended

查看錯誤日誌/var/log/mysql/error3307.log

 

發現是因爲權限問題沒法建立ibdata文件：

 

160218 12:19:09 InnoDB: Completed initialization of buffer pool
160218 12:19:09  InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.
InnoDB: File name ./ibdata1
InnoDB: File operation call: 'create'.
InnoDB: Cannot continue operation.

 

查看目錄，理論上應該有讀寫權限的啊：

ls -ld /var/lib/mysql3307 drwx------ 4 mysql mysql 4096 Feb 18 15:09 /var/lib/mysql3307

 

難道還有其它什麼權限限制？

用dmesg看一下，確實有一些報錯，

 

[4489099.208660] type=1400 audit(1455768562.142:57): apparmor="DENIED" operation="mknod" profile="/usr/sbin/mysqld" name="/var/lib/mysql3307/ibdata1" pid=19775 comm="mysqld" requested_mask="c" denied_mask="c" fsuid=105 ouid=105

 

查看/usr/sbin/mysqld的配置：

 

vi /etc/apparmor.d/usr.sbin.mysqld

 

增長mysql3307目錄的權限，重啓apparmor： 

/var/lib/mysql3307/ r,
 /var/lib/mysql3307/** rwk,

/etc/init.d/apparmor restart

再次從新啓動mysqld，發現仍是報錯，不過此次報錯的信息不同了：

160218 12:44:03 [ERROR] Can't start server : Bind on unix socket: Permission denied
160218 12:44:03 [ERROR] Do you already have another mysqld server running on socket: /var/run/mysqld/mysqld3307.sock ?
160218 12:44:03 [ERROR] Aborting

 

dmesg也能看到錯誤消息：

 

[4491181.040673] type=1400 audit(1455770643.975:99): apparmor="DENIED" operation="mknod" profile="/usr/sbin/mysqld" name="/run/mysqld/mysqld3307.sock" pid=24093 comm="mysqld" requested_mask="c" denied_mask="c" fsuid=105 ouid=105

 

到/etc/apparmor.d/usr.sbin.mysqld增長配置，重啓apparmor

/var/run/mysqld/mysqld3307.pid rw,
 /var/run/mysqld/mysqld3307.sock w,
 /run/mysqld/mysqld3307.pid rw,
 /run/mysqld/mysqld3307.sock w,

  

再次重啓mysqld，仍是報錯，不過此次是新的報錯：

160218 12:57:27 [Note] Server socket created on IP: '0.0.0.0'.
160218 12:57:27 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
160218 12:57:27 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld3307.pid ended

 

跑一下mysql_install_db --defaults-file=/etc/mysql/my3307.cnf

此次mysqld終於能夠正常啓動了：

160218 14:44:59 [Note] Server socket created on IP: '0.0.0.0'.
160218 14:44:59 [Note] Event Scheduler: Loaded 0 events
160218 14:44:59 [Note] /usr/sbin/mysqld: ready for connections.
Version: '5.5.46-0ubuntu0.14.04.2'  socket: '/var/run/mysqld/mysqld3307.sock'  port: 3307  (Ubuntu)