CentSO7环境下，MySQL5.7服务器未启动原因及解决方案

问题背景

重启操作系统后，mysql数据库服务器未能正常启动。

[root@dba mysql-5.7]# bin/mysql -uroot -p
Enter password: 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# systemctl status mysqld.service
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: failed (Result: start-limit) since Fri 2023-04-14 00:03:27 CST; 1min 0s ago
  Process: 1288 ExecStart=/opt/mysql/mysql-5.7/bin/mysqld --defaults-file=/etc/my.cnf --basedir=/opt/mysql/mysql-5.7 --datadir=/opt/mysql/mysql-5.7/data --plugin-dir=/opt/mysql/mysql-5.7/lib/plugin --log-error=/var/log/mysql/error.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock --port=3306 (code=exited, status=1/FAILURE)
 Main PID: 1288 (code=exited, status=1/FAILURE)

Apr 14 00:03:27 dba systemd[1]: Unit mysqld.service entered failed state.
Apr 14 00:03:27 dba systemd[1]: mysqld.service failed.
Apr 14 00:03:27 dba systemd[1]: mysqld.service holdoff time over, scheduling restart.
Apr 14 00:03:27 dba systemd[1]: Stopped MySQL Server.
Apr 14 00:03:27 dba systemd[1]: start request repeated too quickly for mysqld.service
Apr 14 00:03:27 dba systemd[1]: Failed to start MySQL Server.
Apr 14 00:03:27 dba systemd[1]: Unit mysqld.service entered failed state.
Apr 14 00:03:27 dba systemd[1]: mysqld.service failed.
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# 

没有出现错误日志，通过 journalctl -xe 命令查看系统日志确定原因

[root@dba mysql-5.7]# systemctl -l start mysqld.service
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# journalctl -xe
-- 
-- The start-up result is done.
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.731435Z 0 [Warning] Changed limits: max_open_files: 1024 (requested 5000)
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.731524Z 0 [Warning] Changed limits: table_open_cache: 431 (requested 2000)
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.891778Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see dApr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.891831Z 0 [Note] --secure-file-priv is set to NULL. Operations related to importing and exporting data are disabled
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.891870Z 0 [Note] /opt/mysql/mysql-5.7/bin/mysqld (mysqld 5.7.37) starting as process 1335 ...
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.901762Z 0 [ERROR] Could not open file '/var/log/mysql/error.log' for error logging: No such file or directory
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.901833Z 0 [ERROR] Aborting
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.901878Z 0 [Note] Binlog end
Apr 14 00:05:38 dba mysqld[1335]: 2023-04-13T16:05:38.902049Z 0 [Note] /opt/mysql/mysql-5.7/bin/mysqld: Shutdown complete
Apr 14 00:05:38 dba systemd[1]: mysqld.service: main process exited, code=exited, status=1/FAILURE
Apr 14 00:05:38 dba systemd[1]: Unit mysqld.service entered failed state.
Apr 14 00:05:38 dba systemd[1]: mysqld.service failed.
Apr 14 00:05:39 dba systemd[1]: mysqld.service holdoff time over, scheduling restart.
Apr 14 00:05:39 dba systemd[1]: Stopped MySQL Server.
-- Subject: Unit mysqld.service has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit mysqld.service has finished shutting down.
Apr 14 00:05:39 dba systemd[1]: start request repeated too quickly for mysqld.service
Apr 14 00:05:39 dba systemd[1]: Failed to start MySQL 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.
Apr 14 00:05:39 dba systemd[1]: Unit mysqld.service entered failed state.
Apr 14 00:05:39 dba systemd[1]: mysqld.service failed.
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面向ChartGPT解决问题

• 方法2经过尝试未能成功。

问题解决方案

[root@dba mysql-5.7]# sudo touch /var/log/mysql/error.log
touch: cannot touch ‘/var/log/mysql/error.log’: No such file or directory
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# mkdir -pv /var/log/mysql/
mkdir: created directory ‘/var/log/mysql/’
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# touch /var/log/mysql/error.log
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# chown -v mysql:dbgrp /var/log/mysql/error.log 
changed ownership of ‘/var/log/mysql/error.log’ from root:root to mysql:dbgrp
[root@dba mysql-5.7]# 

[root@dba mysql-5.7]# systemctl restart mysqld.service
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]# systemctl status mysqld.service
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Fri 2023-04-14 00:20:23 CST; 177ms ago
 Main PID: 1714 (mysqld)
    Tasks: 2
   Memory: 89.7M
   CGroup: /system.slice/mysqld.service
           └─1714 /opt/mysql/mysql-5.7/bin/mysqld --defaults-file=/etc/my.cnf --basedir=/opt/mysql/mysql-5.7 --datadir=/opt/mysql/mysql-5.7/data --plugin-dir=/opt/mysql/mysql-5.7/lib/plugin...
Apr 14 00:20:23 dba systemd[1]: Started MySQL Server.
[root@dba mysql-5.7]# 
[root@dba mysql-5.7]#