Unable to start MySQL service. Another MySQL daemon is already running with the

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Unable to start MySQL service. Another MySQL daemon is already running with the same UNIX socket


特征

如果你遇到如下所列的任何问题之一,本文也许能帮到你.

    MySQL starts/stops properly when started/stopped with the mysqld service restart, but MySQL does not start when a server is rebooted.
    After upgrading MySQL, binaries mysqld will not start at all.
    After relocating the MySQL datadir or changing the default port, MySQL does not start.

以上所有问题有一个共同特征:你无法使用service mysqld restart/start或其他方式启动mysql.

   
[iyunv@server ~]# /etc/init.d/mysqld start
Another MySQL daemon already running with the same unix socket.
Starting mysqld:                                           [FAILED]


原因

非正常的关闭/停止服务,导致mysqld的socket没有被移除. 该非正常的方式比较常见于:系统断电重启.
解决办法

There are several common cases when the socket file is not removed. Please check the below use cases and apply the appropriate resolution.
1. 查看/var/log/mysqld.log,你会发现类似如下日志:


   
131207 21:15:47 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
/usr/libexec/mysqld: Can't create/write to file '/tmp/ib0h0Wt3' (Errcode: 13)
131207 21:15:47  InnoDB: Error: unable to create temporary file; errno: 13
131207 21:15:47 [ERROR] Plugin 'InnoDB' init function returned error.
131207 21:15:47 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
131207 21:15:47 [Note] Event Scheduler: Loaded 0 events
131207 21:15:47 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.1.71'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution


网上百度到该问题的解决办法都是:
1
   
rm /var/lib/mysql/mysql.sock

1
   
<span style="font-family: monospace;">mv /var/lib/mysql/mysql.sock /var/lib/mysql/mysql.sock.bak</span>

笔者试了很多此,发现还是启动不成功.细看log,文本末尾写着的不只/var/lib/mysql/mysql.sock,还有/var/lib/mysql/mysql1.sock,/var/lib/mysql/mysql22.sock.而我的文件夹目录中也正好存在这些文件.于是猜想, mysql异常关闭之后,不单只产生myql.sock,还有其他sock文件,我将这三个sock文件都重命名后,myql便正常启动了.
1
   
rm /var/lib/mysql/mysql.sock

1
   
rm /var/lib/mysql/mysql1.sock

1
   
rm /var/lib/mysql/mysql22.sock

2. 总结

mysql异常关闭时,产生的sock文件可能存在多个,要将这些sock文件都清除,mysql才能正常启动.



原文链接:Unable to start MySQL service. Another MySQL daemon is already running with the same UNIX socket.