Mysql--Failed to start MySQL 8.0 database server/InnoDB: The innodb_system data file 'ibdata1' must be writable

1. 在手动启动mysql 的服务的时候发现有error ,

2. 然后通过status 查看mysql.service ,发现是“Failed to start MySQL 8.0 database server.” 

[root@localhost mysql]# systemctl start mysqld
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xe" for details.
[root@localhost mysql]# 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 Thu 2021-01-28 12:14:04 CST; 15s ago
Process: 7715 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
Process: 7710 ExecStart=/usr/libexec/mysqld --basedir=/usr (code=exited, status=1/FAILURE)
Process: 7672 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SU>
Process: 7646 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
Main PID: 7710 (code=exited, status=1/FAILURE)
Status: "SERVER_BOOTING"
Error: 2 (No such file or directory)

Jan 28 12:14:04 localhost.localdomain systemd[1]: Starting MySQL 8.0 database server...
Jan 28 12:14:04 localhost.localdomain systemd[1]: mysqld.service: Main process exited, code=exited, sta>
Jan 28 12:14:04 localhost.localdomain systemd[1]: mysqld.service: Failed with result 'exit-code'.
Jan 28 12:14:04 localhost.localdomain systemd[1]: Failed to start MySQL 8.0 database server.

3.再通过mysql log 查看发现是“ibdata1” can't be writable 

[root@localhost mysql]# cat /var/log/mysql.log
cat: /var/log/mysql.log: No such file or directory
[root@localhost mysql]# cat /var/log/mysql/mysqld.log
2021-01-28T04:13:38.121609Z 0 [System] [MY-013169] [Server] /usr/libexec/mysqld (mysqld 8.0.13) initializing of server in progress as process 7487
2021-01-28T04:13:49.083943Z 5 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: Q)s9XxCC(btu
2021-01-28T04:13:55.959881Z 0 [System] [MY-013170] [Server] /usr/libexec/mysqld (mysqld 8.0.13) initializing of server has completed
2021-01-28T04:14:04.430539Z 0 [System] [MY-010116] [Server] /usr/libexec/mysqld (mysqld 8.0.13) starting as process 7710
2021-01-28T04:14:04.442393Z 1 [ERROR] [MY-012271] [InnoDB] The innodb_system data file 'ibdata1' must be writable
2021-01-28T04:14:04.442414Z 1 [ERROR] [MY-012278] [InnoDB] The innodb_system data file 'ibdata1' must be writable
2021-01-28T04:14:04.442427Z 1 [ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine
2021-01-28T04:14:04.442501Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed.
2021-01-28T04:14:04.442521Z 0 [ERROR] [MY-010119] [Server] Aborting
2021-01-28T04:14:04.442767Z 0 [System] [MY-010910] [Server] /usr/libexec/mysqld: Shutdown complete (mysqld 8.0.13)  Source distribution.

去到mysql 路径下check 该文件的权限

[root@localhost mysql]# ll /var/lib/mysql/
total 155700
drwxr-x--- 2 root  root         6 Jan 28 12:13 '#innodb_temp'
-rw-r----- 1 root  root        56 Jan 28 12:13  auto.cnf
-rw-r----- 1 mysql mysql        0 Jan 28 12:14  binlog.index
-rw------- 1 root  root      1680 Jan 28 12:13  ca-key.pem
-rw-r--r-- 1 root  root      1112 Jan 28 12:13  ca.pem
-rw-r--r-- 1 root  root      1112 Jan 28 12:13  client-cert.pem
-rw------- 1 root  root      1676 Jan 28 12:13  client-key.pem
-rw-r----- 1 root  root      5753 Jan 28 12:13  ib_buffer_pool
-rw-r----- 1 root  root  50331648 Jan 28 12:13  ib_logfile0
-rw-r----- 1 root  root  50331648 Jan 28 12:13  ib_logfile1
-rw-r----- 1 root  root  12582912 Jan 28 12:13  ibdata1
drwxr-x--- 2 root  root       143 Jan 28 12:13  mysql
-rw-r----- 1 root  root  25165824 Jan 28 12:13  mysql.ibd
drwxr-x--- 2 root  root      4096 Jan 28 12:13  performance_schema
-rw------- 1 root  root      1676 Jan 28 12:13  private_key.pem
-rw-r--r-- 1 root  root       452 Jan 28 12:13  public_key.pem
-rw-r--r-- 1 root  root      1112 Jan 28 12:13  server-cert.pem
-rw------- 1 root  root      1676 Jan 28 12:13  server-key.pem
drwxr-x--- 2 root  root        28 Jan 28 12:13  sys
-rw-r----- 1 root  root  10485760 Jan 28 12:13  undo_001
-rw-r----- 1 root  root  10485760 Jan 28 12:13  undo_002
[root@localhost mysql]#

chown mysql.mysql -R /var/lib/mysql

然后stop mysql.service ,最后再发start mysql.service 就可以了。