mariadb(mysql)起動しなくなった場合

OS: centos7

journalctl -xe

 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [Note] InnoDB: Using SSE4.2 crc32 instructions
 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [Note] InnoDB: Initializing buffer pool, total size = 134217728, chunk size = 134
 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [Note] InnoDB: Completed initialization of buffer pool
 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread pr
 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [ERROR] InnoDB: Upgrade after a crash is not supported. The redo log was created
 8月 14 23:09:01 cent74 mariadbd[8773]: 2020-08-14 23:09:01 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [Note] InnoDB: Starting shutdown...
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [ERROR] Plugin 'InnoDB' init function returned error.
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [Note] Plugin 'FEEDBACK' is disabled.
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [ERROR] Unknown/unsupported storage engine: InnoDB
 8月 14 23:09:02 cent74 mariadbd[8773]: 2020-08-14 23:09:02 0 [ERROR] Aborting
 8月 14 23:09:02 cent74 systemd[1]: mariadb.service: main process exited, code=exited, status=1/FAILURE
 8月 14 23:09:02 cent74 systemd[1]: Failed to start MariaDB 10.5.5 database server.
-- Subject: Unit mariadb.service has failed
-- Defined-By: systemd

上記ファイルを削除

/var/lib/mysql/ib_logfile0
/var/lib/mysql/ib_logfile1
/var/lib/mysql/ib_logfile101

再起動

systemctl restart mariadb