Как выяснить почему не запускается MySQL?

Все было хорошо. НО! Вдруг я пытаюсь подключиться к БД, а она посылает меня куда подальше. В чем может быть дело?
У меня Centos7.

Я ни разу не сис-админ. Поэтому не понимаю, что мне пытаются сказать тут. Может надо еще больше инфы подкинуть, чтобы понять в чем дело?

[app@pervichka ~]$ sudo service mysqld start Redirecting to /bin/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.

[app@pervichka ~]$ systemctl status mysqld.service ● mysqld.service — MySQL Server Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled) Active: failed (Result: start-limit) since Wed 2017-09-20 16:55:54 MSK; 10s ago Docs: man:mysqld(8) dev.mysql.com/doc/refman/en/using-systemd.html Process: 4918 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=1/FAILURE) Process: 4896 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS) Sep 20 16:55:54 pervichka systemd[1]: Failed to start MySQL Server. Sep 20 16:55:54 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service failed. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service holdoff time over, scheduling restart. Sep 20 16:55:54 pervichka systemd[1]: start request repeated too quickly for mysqld.service Sep 20 16:55:54 pervichka systemd[1]: Failed to start MySQL Server. Sep 20 16:55:54 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service failed.

[app@pervichka ~]$ journalctl -xe Sep 20 16:55:50 pervichka systemd[1]: mysqld.service: control process exited, code=exited status=1 Sep 20 16:55:50 pervichka systemd[1]: Failed to start MySQL Server. — Subject: Unit mysqld.service has failed — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has failed. — -- The result is failed. Sep 20 16:55:50 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:50 pervichka systemd[1]: mysqld.service failed. Sep 20 16:55:50 pervichka systemd[1]: mysqld.service holdoff time over, scheduling restart. Sep 20 16:55:50 pervichka systemd[1]: Starting MySQL Server… — Subject: Unit mysqld.service has begun start-up — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has begun starting up. Sep 20 16:55:52 pervichka mysqld[4879]: Initialization of mysqld failed: 0 Sep 20 16:55:52 pervichka systemd[1]: mysqld.service: control process exited, code=exited status=1 Sep 20 16:55:52 pervichka systemd[1]: Failed to start MySQL Server. — Subject: Unit mysqld.service has failed — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has failed. — -- The result is failed. Sep 20 16:55:52 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:52 pervichka systemd[1]: mysqld.service failed. Sep 20 16:55:52 pervichka systemd[1]: mysqld.service holdoff time over, scheduling restart. Sep 20 16:55:52 pervichka systemd[1]: Starting MySQL Server… — Subject: Unit mysqld.service has begun start-up — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has begun starting up. Sep 20 16:55:54 pervichka mysqld[4918]: Initialization of mysqld failed: 0 Sep 20 16:55:54 pervichka systemd[1]: mysqld.service: control process exited, code=exited status=1 Sep 20 16:55:54 pervichka systemd[1]: Failed to start MySQL Server. — Subject: Unit mysqld.service has failed — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has failed. — -- The result is failed. Sep 20 16:55:54 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service failed. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service holdoff time over, scheduling restart. Sep 20 16:55:54 pervichka systemd[1]: start request repeated too quickly for mysqld.service Sep 20 16:55:54 pervichka systemd[1]: Failed to start MySQL Server. — Subject: Unit mysqld.service has failed — Defined-By: systemd — Support: lists.freedesktop.org/mailman/listinfo/systemd-devel — -- Unit mysqld.service has failed. — -- The result is failed. Sep 20 16:55:54 pervichka systemd[1]: Unit mysqld.service entered failed state. Sep 20 16:55:54 pervichka systemd[1]: mysqld.service failed. lines 3140-3200/3200 (END)