Sharing examples of solutions to MySQL failure to start

This article mainly introduces the relevant information about the solution to the problem that MySQL cannot be started. I hope that through this article, everyone can solve the problem of the database not being able to start. Friends in need can refer to

MySQL cannot be started. Solution

MySQL cannot start

After stopping mysql, I performed some operations (such as modifying the host name), restarted mysql, and found that it could not start.

[root@www ~]$ service mysql start 
Starting MySQL..^[[A.................................................................................................. ERROR! The server quit without updating PID file (/disk/mysql/www.pid).
[root@www ~]$ service mysql stop 
 ERROR! MySQL server PID file could not be found!
[root@www ~]$ service mysql stop 
 ERROR! MySQL server PID file could not be found!
[root@www ~]$ service mysql start 
Starting MySQL..................
还是老样子，只好 Ctr+C 掉。
[root@www ~]$

It really can’t be started. Check the log: /disk/mysql/www.err

120608 09:56:17 mysqld_safe Starting mysqld daemon with databases from /disk/mysql
120608 9:56:17 [Note] Plugin 'FEDERATED' is disabled.
120608 9:56:17 InnoDB: The InnoDB memory heap is disabled
120608 9:56:17 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
120608 9:56:17 InnoDB: Compressed tables use zlib 1.2.3
120608 9:56:17 InnoDB: Using Linux native AIO
120608 9:56:17 InnoDB: Initializing buffer pool, size = 128.0M
120608 9:56:17 InnoDB: Completed initialization of buffer pool
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
120608 9:56:17 InnoDB: Retrying to lock the first data file
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
InnoDB: Check that you do not already have another mysqld process
InnoDB: using the same InnoDB data or log files.
InnoDB: Unable to lock ./ibdata1, error: 11
...

It seems that the original mysqld did not stop.

Forced termination of mysqld

[root@www ~]$ ps -ef|grep mysql 
root   4769   1 0 Jun06 ?    00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/disk/mysql --pid-file=/disk/mysql/localhost.pid
mysql   4874 4769 0 Jun06 ?    00:04:04 /usr/sbin/mysqld --basedir=/usr --datadir=/disk/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/disk/mysql/localhost.err --pid-file=/disk/mysql/localhost.pid --socket=/disk/mysql/mysql.sock
root   17947   1 0 09:56 pts/1  00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/disk/mysql --pid-file=/disk/mysql/www.pid
mysql  18052 17947 0 09:56 pts/1  00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/disk/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --log-error=/disk/mysql/www.err --pid-file=/disk/mysql/www.pid --socket=/disk/mysql/mysql.sock
root   18099 17514 0 09:56 pts/1  00:00:00 grep mysql
[root@www ~]$ killall mysqld 
[root@www ~]$ killall mysqld 
[root@www ~]$ ps -ef|grep mysql 
root   18116 17514 0 09:57 pts/1  00:00:00 grep mysql
[root@www ~]$

Start mysqld, and now there is no problem in executing the startup command multiple times.

[root@www ~]$ service mysql start 
Starting MySQL. SUCCESS! 
[root@www ~]$ 
[root@www ~]$ 
[root@www ~]$ 
[root@www ~]$ 
[root@www ~]$ service mysql start 
Starting MySQL SUCCESS! 
[root@www ~]$

What is the error: 11 shown in the www.err file earlier? Let’s take a look:

[root@www ~]$ perror 11 
OS error code 11: Resource temporarily unavailable
[root@www ~]$ 
[root@www ~]$

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