Losing data in Vagrant after restart or destroy

Question

I am new to Vagrant and have a couple of questions.

Sometimes when I restart my computer or destroy my vagrant the whole MySQL database is wiped out. I tried to find some answers about this on stackoverflow but didn't have any luck so far.

So my questions are:

1) Where does the data get stored?

2) Why do I sometimes lose data?

3) If so how do I keep the data after restart of destroy?