Fedora Linux下无法启动MySQL服务的问题求助

问题背景 #

学习Web开发时，尝试为Spring Boot应用搭建MySQL数据库，使用sudo dnf install mysql-community-server安装后，无法启动MySQL服务。

错误现象 #

执行以下命令后出现对应错误：

• 连接MySQL失败：

$ mysql
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111)

• 查看版本正常：

$ mysql --version
mysql  Ver 8.0.31 for Linux on x86_64 (MySQL Community Server - GPL)

• 启动服务失败：

$ sudo service mysql start
Redirecting to /bin/systemctl start mysql.service
Failed to start mysql.service: Unit mysql.service not found.

$ sudo systemctl start mysqld
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xeu mysqld.service" for details.

• 服务状态信息：

$ systemctl status mysqld.service
× mysqld.service - MySQL Server
     Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; preset: disabled)
     Active: failed (Result: exit-code) since Wed 2022-11-30 06:22:00 IST; 4s ago
       Docs: man:mysqld(8)
             http://dev.mysql.com/doc/refman/en/using-systemd.html
    Process: 3783 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
    Process: 3818 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS (code=exited, status=1/FAILURE)
   Main PID: 3818 (code=exited, status=1/FAILURE)
     Status: "Server shutdown complete"
      Error: 22 (Invalid argument)
        CPU: 1.043s

Nov 30 06:21:59 fedora systemd[1]: Starting mysqld.service - MySQL Server...
Nov 30 06:22:00 fedora systemd[1]: mysqld.service: Main process exited, code=exited, status=1/FAILURE
Nov 30 06:22:00 fedora systemd[1]: mysqld.service: Failed with result 'exit-code'.
Nov 30 06:22:00 fedora systemd[1]: Failed to start mysqld.service - MySQL Server.
Nov 30 06:22:00 fedora systemd[1]: mysqld.service: Consumed 1.043s CPU time.

配置文件信息 #

$ cat /etc/my.cnf
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/8.0/en/server-configuration-defaults.html

[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 the leading "# " to disable binary logging
# Binary logging captures changes between backups and is enabled by
# default. It's default setting is log_bin=binlog
# disable_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
#
# Remove leading # to revert to previous value for default_authentication_plugin,
# this will increase compatibility with older clients. For background, see:
# https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_default_authentication_plugin
# default-authentication-plugin=mysql_native_password

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

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

$ cat /etc/mysql/my.cnf
cat: /etc/mysql/my.cnf: No such file or directory

$ cat /var/lib/mysql/my.cnf
cat: /var/lib/mysql/my.cnf: No such file or directory

补充日志信息 #

journalctl日志 #

$ journalctl -xeu mysqld.service
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ An ExecStart= process belonging to unit mysqld.service has exited.
░░ 
░░ The process' exit code is 'exited' and its exit status is 1.
Nov 30 06:22:00 fedora systemd[1]: mysqld.service: Failed with result 'exit-code'.
░░ Subject: Unit failed
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ The unit mysqld.service has entered the 'failed' state with result 'exit-code'.
Nov 30 06:22:00 fedora systemd[1]: Failed to start mysqld.service - MySQL Server.
░░ Subject: A start job for unit mysqld.service has failed
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ A start job for unit mysqld.service has finished with a failure.
░░ 
░░ The job identifier is 3531 and the job result is failed.
Nov 30 06:22:00 fedora systemd[1]: mysqld.service: Consumed 1.043s CPU time.
░░ Subject: Resources consumed by unit runtime
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ The unit mysqld.service completed and consumed the indicated resources.

/var/log/mysqld.log日志 #

2022-11-30T00:44:42.089067Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.31) initializing of server in progress as process 1064
2022-11-30T00:44:42.091892Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2022-11-30T00:44:42.091960Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
2022-11-30T00:44:42.092006Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:44:42.092083Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.
2022-11-30T00:44:42.331797Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.31) starting as process 1069
2022-11-30T00:44:42.339299Z 0 [Warning] [MY-010075] [Server] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 2d9a3bde-7048-11ed-a7cd-f406413544b8.
2022-11-30T00:44:42.342844Z 1 [ERROR] [MY-011011] [Server] Failed to find valid data directory.
2022-11-30T00:44:42.342942Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed.
2022-11-30T00:44:42.342960Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:44:42.343234Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.
2022-11-30T00:49:37.543811Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.31) initializing of server in progress as process 3714
2022-11-30T00:49:37.544916Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2022-11-30T00:49:37.544934Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
2022-11-30T00:49:37.545003Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:49:37.545083Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.
2022-11-30T00:49:37.768975Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.31) starting as process 3719
2022-11-30T00:49:37.773567Z 1 [ERROR] [MY-011011] [Server] Failed to find valid data directory.
2022-11-30T00:49:37.773672Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed.
2022-11-30T00:49:37.773705Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:49:37.774047Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.
2022-11-30T00:52:00.113630Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.31) initializing of server in progress as process 3813
2022-11-30T00:52:00.114677Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2022-11-30T00:52:00.114695Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
2022-11-30T00:52:00.114738Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:52:00.114840Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.
2022-11-30T00:52:00.358242Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.31) starting as process 3818
2022-11-30T00:52:00.362438Z 1 [ERROR] [MY-011011] [Server] Failed to find valid data directory.
2022-11-30T00:52:00.362537Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed.
2022-11-30T00:52:00.362566Z 0 [ERROR] [MY-010119] [Server] Aborting
2022-11-30T00:52:00.362844Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.31)  MySQL Community Server - GPL.

解决方案 #

从日志里的--initialize specified but the data directory has files in it和Failed to find valid data directory可以看出，问题出在MySQL数据目录/var/lib/mysql里有残留文件，导致初始化失败。按以下步骤操作：

1. 先停止MySQL服务（如果处于错误启动状态）：

sudo systemctl stop mysqld

2. 备份数据目录里的文件（可选，防止有需要保留的数据）：

sudo cp -r /var/lib/mysql /var/lib/mysql_backup

3. 删除数据目录里的所有文件：

sudo rm -rf /var/lib/mysql/*

4. 重新初始化MySQL：

sudo mysqld --initialize --user=mysql

5. 启动MySQL服务：

sudo systemctl start mysqld

6. 查看服务状态确认是否正常：

systemctl status mysqld

7. 初始密码会在/var/log/mysqld.log里，搜索temporary password获取：

sudo grep 'temporary password' /var/log/mysqld.log

用这个密码登录MySQL，然后修改密码：

mysql -uroot -p
ALTER USER 'root'@'localhost' IDENTIFIED BY '你的新密码';

注意事项 #

• 确保操作时使用sudo获取足够权限，避免权限不足导致的文件删除/初始化失败。
• 如果之前有重要数据，一定要先备份，避免数据丢失。

内容的提问来源于stack exchange，提问作者Prad