mysql—Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.

一、问题

MySQL启动时提示如下错误：

[ck@hadoop102 conf]$ sudo systemctl start mysqld.service
[sudo] atguigu 的密码：
Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.

二、原因分析

查看日志分析

[root@hadoop102 conf]# journalctl -xe
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit mysqld.service has failed.
-- 
-- The result is failed.
2月 08 09:50:30 hadoop102 systemd[1]: Unit mysqld.service entered failed state.
2月 08 09:50:30 hadoop102 systemd[1]: mysqld.service failed.
2月 08 09:50:31 hadoop102 setroubleshoot[5663]: SELinux is preventing /usr/sbin/mysqld from write access on the file ibdata1. For comple
2月 08 09:50:31 hadoop102 python[5663]: SELinux is preventing /usr/sbin/mysqld from write access on the file ibdata1.
                                         
                                         *****  Plugin catchall_labels (83.8 confidence) suggests   *******************
                                         
                                         If you want to allow mysqld to have write access on the ibdata1 file
                                         Then you need to change the label on ibdata1
                                         Do
                                         # semanage fcontext -a -t FILE_TYPE 'ibdata1'
                                         where FILE_TYPE is one of the following: afs_cache_t, faillog_t, hugetlbfs_t, initrc_tmp_t, krb
                                         Then execute:
                                         restorecon -v 'ibdata1'
                                         
                                         
                                         *****  Plugin catchall (17.1 confidence) suggests   **************************
                                         
                                         If you believe that mysqld should be allowed write access on the ibdata1 file by default.
                                         Then you should report this as a bug.
                                         You can generate a local policy module to allow this access.
                                         Do
                                         allow this access for now by executing:
                                         # ausearch -c 'mysqld' --raw | audit2allow -M my-mysqld
                                         # semodule -i my-mysqld.pp
                                         
2月 08 09:50:31 hadoop102 systemd[1]: mysqld.service holdoff time over, scheduling restart.
2月 08 09:50:31 hadoop102 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.
2月 08 09:50:31 hadoop102 systemd[1]: Starting MySQL 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.

selinux限制导致mysql服务启动失败

三、解决办法

[root@hadoop102 conf]# getenforce     （查看selinux状态）
Enforcing
[root@hadoop102 conf]# setenforce 0    （临时关闭）
[root@hadoop102 conf]# vim /etc/selinux/config     （永久关闭，将SELINUX=enforcing改为SELINUX=disabled，保存后退出）  
[root@hadoop102 conf]# getenforce              
Permissive
[root@hadoop102 conf]# systemctl start mysqld.service
[root@hadoop102 conf]# systemctl status mysqld.service
● mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since 一 2021-02-08 10:02:40 CST; 42s ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 6370 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 6346 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 6372 (mysqld)
    Tasks: 27
   CGroup: /system.slice/mysqld.service
           └─6372 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.259391Z 0 [Note] Skipping generation of SSL certificates as ce...ectory.
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.283310Z 0 [Warning] CA certificate ca.pem is self signed.
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.283368Z 0 [Note] Skipping generation of RSA key pair as key fi...ectory.
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.340104Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.396911Z 0 [Note] IPv6 is available.
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.396987Z 0 [Note]   - '::' resolves to '::';
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.397056Z 0 [Note] Server socket created on IP: '::'.
2月 08 10:02:39 hadoop102 mysqld[6370]: 2021-02-08T02:02:39.399136Z 0 [Note] InnoDB: Buffer pool(s) load completed at 2102...0:02:39
2月 08 10:02:40 hadoop102 mysqld[6370]: 2021-02-08T02:02:40.123553Z 0 [Note]
2月 08 10:02:40 hadoop102 systemd[1]: Started MySQL Server.
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[root@hadoop102 conf]#