Problem of not starting after restarting mongodb server

Environment: centos 7 mongodb 2.6

Question: Mongodb is installed and running.
If you restart this server, it should be added to auto start and Mongo should be auto start, but it didn't run, so I checked it.

/var/lib/mongo local could not be opened

This error message did not start.

I was testing it, so I boldly deleted all the contents of the folder, so it started.

But I don't want to do this when I actually do service, so I'd like to know a fundamental solution.

In the case of mongodb, when the server is restarted, does it not just restart? How can I restart mongodb after restarting the server... Please give me an answer.