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

特征

假设你遇到例如以下所列的不论什么问题之中的一个,本文或许能帮到你.

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.

以上全部问题有一个共同特征:你无法使用service mysqld restart/start或其它方式启动mysql.

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[root@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. 该非正常的方式比較常见于:系统断电重新启动.

解决的方法

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,你会发现相似例如以下日志:

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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的方法都是:

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rm /var/lib/mysql/mysql.sock

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

笔者试了非常多此,发现还是启动不成功.细看log,文本末尾写着的不仅仅/var/lib/mysql/mysql.sock,还有/var/lib/mysql/mysql1.sock,/var/lib/mysql/mysql22.sock.而我的文件夹文件夹中也正好存在这些文件.于是猜想, mysql异常关闭之后,不单仅仅产生myql.sock,还有其它sock文件,我将这三个sock文件都重命名后,myql便正常启动了.

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rm /var/lib/mysql/mysql.sock

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rm
/var/lib/mysql/mysql1.sock

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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才干正常启动.

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

参考:http://kb.sp.parallels.com/en/119334