mysql 5.6.25启动不起来

mysql 关机启动不起来。

又不报错

环境：

centos 7

mysql 5.6.25

log-error=/var/log/mysqld.log

pid-file=/var/run/mysqld/mysqld.pid

[root@WIN-P11PIHOSG63 ~]# tail -20 /var/log/mysqld.log

2016-03-04 14:02:31 5201 [Note] Shutting down plugin 'INNODB_LOCKS'

2016-03-04 14:02:31 5201 [Note] Shutting down plugin 'INNODB_TRX'

2016-03-04 14:02:31 5201 [Note] Shutting down plugin 'InnoDB'

2016-03-04 14:02:31 5201 [Note] InnoDB: FTS optimize thread exiting.

2016-03-04 14:02:31 5201 [Note] InnoDB: Starting shutdown...

2016-03-04 14:02:33 5201 [Note] InnoDB: Shutdown completed; log sequence number 808362591

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'PERFORMANCE_SCHEMA'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'ARCHIVE'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'BLACKHOLE'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'MEMORY'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'CSV'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'MyISAM'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'MRG_MYISAM'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'sha256_password'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'mysql_old_password'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'mysql_native_password'

2016-03-04 14:02:33 5201 [Note] Shutting down plugin 'binlog'

2016-03-04 14:02:33 5201 [Note] /usr/sbin/mysqld: Shutdown complete

160304 14:02:34 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended

[root@WIN-P11PIHOSG63 ~]# ls -ld /var/run/mysqld/

my.cnf

[mysqld]

#

# Remove leading # and set to the amount of RAM for the most important data

# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.

# innodb_buffer_pool_size = 128M

#

# Remove leading # to turn on a very important data integrity option: logging

# changes to the binary log between backups.

# log_bin

#

# Remove leading # to set options mainly useful for reporting servers.

# The server defaults are faster for transactions and fast SELECTs.

# Adjust sizes as needed, experiment to find the optimal values.

# join_buffer_size = 128M

# sort_buffer_size = 2M

# read_rnd_buffer_size = 2M

basedir=/usr

datadir=/var/lib/mysql

tmpdir=/tmp

socket=/var/lib/mysql/mysql.sock

#slave_load_tmpdir=/tmp

#symbolic-links=0

#skip-name-resolve

##skip-symbolic-links

#max_connect_errors = 10000

#max_connections = 500

#wait-timeout = 30

#new add dba

#binlog-format=ROW

#log-bin=master-bin

#log-slave-updates=true

#gtid-mode=on

#enforce-gtid-consistency=true

#master-info-repository=TABLE

#relay-log-info-repository=TABLE

#sync-master-info=1

#slave-parallel-workers=2

#binlog-checksum=CRC32

#master-verify-checksum=1

#slave-sql-verify-checksum=1

#binlog-rows-query-log_events=1

server-id=1

#report-port=3306

port=3306

#report-host=WIN-P11PIHOSG63.lan

#rpl_semi_sync_master_enabled=ON

# Recommended in standard MySQL setup

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

解决：

[mysqld_safe]

log-error=/var/log/mysqld.log

#pid-file=/var/run/mysqld/mysqld.pid #注释掉这行

service mysqld start

或者

/bin/systemctl start mysqld.service

赠送思路：

今天，启动MySQL服务器失败，如下所示：

[root@spark01 ~]# /etc/init.d/mysqld start
Starting mysqld (via systemctl):  Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.
[FAILED]

根据提示，分别使用systemctl status mysqld.service和journalctl -xe查看服务启动失败的原因

[root@spark01 ~]# systemctl status mysqld.service

?.mysqld.service - SYSV: MySQL database server.
Loaded: loaded (/etc/rc.d/init.d/mysqld)
Active: failed (Result: exit-code) since Wed 2016-01-20 18:26:57 CST; 40s ago
Docs: man:systemd-sysv-generator(8)
Process: 2979 ExecStart=/etc/rc.d/init.d/mysqld start (code=exited, status=1/FAILURE)

Jan 20 18:26:56 spark01 systemd[1]: Starting SYSV: MySQL database server....
Jan 20 18:26:57 spark01 mysqld[2979]: MySQL Daemon failed to start.
Jan 20 18:26:57 spark01 mysqld[2979]: Starting mysqld:  [FAILED]
Jan 20 18:26:57 spark01 systemd[1]: mysqld.service: control process exited, code=exited status=1
Jan 20 18:26:57 spark01 systemd[1]: Failed to start SYSV: MySQL database server..
Jan 20 18:26:57 spark01 systemd[1]: Unit mysqld.service entered failed state.
Jan 20 18:26:57 spark01 systemd[1]: mysqld.service failed.

[root@spark01 ~]# journalctl -xe

--
-- Unit session-2.scope has begun starting up.
Jan 20 18:26:48 spark01 sshd[2916]: pam_unix(sshd:session): session opened for user spark by (uid=0)
Jan 20 18:26:52 spark01 su[2944]: (to root) spark on pts/1
Jan 20 18:26:52 spark01 su[2944]: pam_unix(su-l:session): session opened for user root by spark(uid=1000)
Jan 20 18:26:56 spark01 polkitd[909]: Registered Authentication Agent for unix-process:2974:117137 (system bus name :1.25
Jan 20 18:26:56 spark01 systemd[1]: Starting SYSV: MySQL database server....
-- Subject: Unit mysqld.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --
-- Unit mysqld.service has begun starting up.
Jan 20 18:26:57 spark01 mysqld[2979]: MySQL Daemon failed to start.
Jan 20 18:26:57 spark01 mysqld[2979]: Starting mysqld:  [FAILED]
Jan 20 18:26:57 spark01 systemd[1]: mysqld.service: control process exited, code=exited status=1
Jan 20 18:26:57 spark01 systemd[1]: Failed to start SYSV: MySQL database server..
-- Subject: Unit mysqld.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --
-- Unit mysqld.service has failed.
--
-- The result is failed.
Jan 20 18:26:57 spark01 systemd[1]: Unit mysqld.service entered failed state.
Jan 20 18:26:57 spark01 systemd[1]: mysqld.service failed.
Jan 20 18:26:57 spark01 polkitd[909]: Unregistered Authentication Agent for unix-process:2974:117137 (system bus name :1.

但，可惜的时，这些信息并不能提供服务启动失败的真正原因。

这时候，不妨打开MySQL的告警日志，毕竟，只要MySQL服务启动，告警日志都会有输出信息的，果然

2016-01-20T10:00:19.935771Z 0 [ERROR] /usr/sbin/mysqld: Can't create/write to file '/var/run/mysqld/mysqld.pid' (Errcode: 2 - No such file or directory)
2016-01-20T10:00:19.935795Z 0 [ERROR] Can't start server: can't create PID file: No such file or directory
160120 18:00:20 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended

MySQL服务在启动的时候，不能创建pid文件。

在终端看一下该目录是否存在，果然，不存在。

于是，创建了/var/run/mysqld/目录，重启MySQL服务

[root@spark01 ~]# mkdir -p /var/run/mysqld/

[root@spark01 ~]# /etc/init.d/mysqld start

Starting mysqld (via systemctl):  Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.
[FAILED]

依旧报错，重新查看告警日志，有以下输出

2016-01-20T10:28:37.183387Z 0 [ERROR] /usr/sbin/mysqld: Can't create/write to file '/var/run/mysqld/mysqld.pid' (Errcode: 13 - Permission denied)
2016-01-20T10:28:37.183431Z 0 [ERROR] Can't start server: can't create PID file: Permission denied
160120 18:28:37 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
160120 18:32:06 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

原来，/var/run/mysqld/的属主和属组还是root，mysql并不能在其中创建文件，后修改该目录的属主和属组，启动OK。

[root@spark01 ~]# ls -ld /var/run/mysqld/
drwxr-xr-x 2 root root 40 Jan 20 18:28 /var/run/mysqld/
[root@spark01 ~]# chown mysql.mysql /var/run/mysqld/
[root@spark01 ~]# /etc/init.d/mysqld start
Starting mysqld (via systemctl):                           [  OK  ]

总结：

以前在玩Kubernetes的时候，常遇到启动失败的情况，根据systemctl的提示，通过systemctl status mysqld.service和journalctl -xe命令查看服务启动失败的原因往往并不如人意，反而给了一种错误的暗示，以为这个跟系统有关。其实，通过查看服务的日志，往往更能清晰的知道服务启动失败的原因。

参考： http://www.cnblogs.com/ivictor/p/5146247.html