170110 5:35:23 [Note] /usr/libexec/mysqld: Normal shutdown
170110 5:35:23 [Note] Event Scheduler: Purging the queue. 0 events
170110 5:35:23 InnoDB: Starting shutdown...
170110 5:35:24 InnoDB: Shutdown completed; log sequence number 0 12765401
170110 5:35:24 [Note] /usr/libexec/mysqld: Shutdown complete
170110 05:35:24 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
This could be an accidental shutdown or the work of hackers which is something that I have before. Finding the cause is another issue as there is no MySQL logging of when and what user initiated the shutdown.