title: Can't start mysql server
body: <p>After rebooting server, I can't start mysql again</p>
  
  <p>I received this message:</p>
  
  <pre><code>Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
  </code></pre>
  
  <p>I tried <strong>journalctl -xe</strong> and received this</p>
  
  <pre><code>-- Subject: Unit mysql.service has failed
  -- Defined-By: systemd
  -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
  -- 
  -- Unit mysql.service has failed.
  -- 
  -- The result is failed.
  Nov 06 21:25:57 myserver systemd[1]: mysql.service: Unit entered failed state.
  Nov 06 21:25:57 myserver systemd[1]: mysql.service: Failed with result 'exit-code'.
  Nov 06 21:25:57 myserver systemd[1]: mysql.service: Service hold-off time over, scheduling restart.
  Nov 06 21:25:57 myserver systemd[1]: Stopped MySQL Community Server.
  -- Subject: Unit mysql.service has finished shutting down
  -- Defined-By: systemd
  -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
  -- 
  -- Unit mysql.service has finished shutting down.
  Nov 06 21:25:57 myserver systemd[1]: Starting MySQL Community Server...
  -- Subject: Unit mysql.service has begun start-up
  -- Defined-By: systemd
  -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
  -- 
  -- Unit mysql.service has begun starting up.
  Nov 06 21:25:58 myserver systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE
  </code></pre>
  
  <p>here is the result for <strong>systemctl status mysql.service</strong></p>
  
  <pre><code>● mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: activating (start-post) (Result: exit-code) since Sun 2016-11-06 21:29:00 UTC; 21s ago
    Process: 4563 ExecStart=/usr/sbin/mysqld (code=exited, status=1/FAILURE)
    Process: 4560 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
   Main PID: 4563 (code=exited, status=1/FAILURE);         : 4566 (mysql-systemd-s)
      Tasks: 2
     Memory: 320.0K
        CPU: 400ms
     CGroup: /system.slice/mysql.service
             └─control
               ├─4566 /bin/bash /usr/share/mysql/mysql-systemd-start post
               └─4625 sleep 1
  
  Nov 06 21:29:00 myserver systemd[1]: Starting MySQL Community Server...
  Nov 06 21:29:01 myserver systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE
  </code></pre>
  
  <p>Please help ! Thank you!</p>