mysql 8 不能启动_data dictionary upgrade from mysql 5.7 in progress

问题：

启动

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

查看状态：

systemctl status mysqld.service
   mysqld.service - MySQL 8.0 database server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Mon 2020-04-20 06:37:28 EDT; 11s ago
  Process: 17057 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
  Process: 17042 ExecStart=/usr/libexec/mysqld --basedir=/usr (code=exited, status=1/FAILURE)
  Process: 17005 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SUCCESS)
  Process: 16980 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
 Main PID: 17042 (code=exited, status=1/FAILURE)
   Status: "Data Dictionary upgrade from MySQL 5.7 in progress"
    Error: 2 (No such file or directory)

Apr 20 06:37:26 lsf1p13 systemd[1]: Starting MySQL 8.0 database server...
Apr 20 06:37:27 lsf1p13 systemd[1]: mysqld.service: Main process exited, code=exited, status=1/FAILURE
Apr 20 06:37:28 lsf1p13 systemd[1]: mysqld.service: Failed with result 'exit-code'.
Apr 20 06:37:28 lsf1p13 systemd[1]: Failed to start MySQL 8.0 database server.

解决办法：

如果是root 可以省略1，2 两步

1. 检查权限： ls -l /var/lib/ | grep mysql
drwxr-xr-x   5 mysql          mysql           270 Apr 20 06:38 mysql
drwxr-x---   2 mysql          mysql             6 Aug  7  2019 mysql-files
drwx------   2 mysql          mysql             6 Aug  7  2019 mysql-keyring

2. 如果没有权限赋权限 ，hmod -R 777 /var/lib/mysql

3.  删除mysql  下的内容，肯能里面的内容有冲突引起的，rm -rf /var/lib/mysql/*

4. 启动mysql, systemctl start mysqld.service

5. 查看状态：

systemctl statys mysqld.service
Unknown operation statys.
[root@lsf1p13 playbook]# systemctl status mysqld.service
   mysqld.service - MySQL 8.0 database server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2020-04-20 06:47:12 EDT; 22s ago
  Process: 17278 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
  Process: 17600 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, status=0/SUCCESS)
  Process: 17472 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SUCCESS)
  Process: 17447 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
 Main PID: 17558 (mysqld)
   Status: "Server is operational"
    Tasks: 39
   Memory: 593.1M
   CGroup: /system.slice/mysqld.service
           └─17558 /usr/libexec/mysqld --basedir=/usr

Apr 20 06:47:03 lsf1p13 systemd[1]: Starting MySQL 8.0 database server...
Apr 20 06:47:04 lsf1p13 mysql-prepare-db-dir[17472]: Initializing MySQL database
Apr 20 06:47:12 lsf1p13 systemd[1]: Started MySQL 8.0 database server.