How to find out why MySQL won't start?

A

Alexander Petrov2017-09-20 16:57:38

MySQL

Alexander Petrov, 2017-09-20 16:57:38

Everything was fine. BUT! Suddenly I try to connect to the database, and it sends me to hell. What can be wrong?
I have centos7.
I have never been a sysadmin. So I don't understand what they are trying to tell me here. Maybe you need to throw more information in order to understand what's going on?

[[email protected] ~]$ 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.

[[email protected] ~]$ 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)
           http://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.

[[email protected] ~]$ 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: http://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: http://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: http://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: http://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: http://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: http://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.
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Max Kostikov, 2017-09-20
@mxms

View the log in the MySQL working directory. It is usually named hostname.err