It's unlikely that what you need to store is too big for a DB but not to big for your file system. The real questions
you should be asking when deciding which to use a things like:
Are there many different types of data? If so, you might want a DB with a table for each type.
Are there non-trivial relationships among the data? If so, you might want a DB to help model those relationships.
Do you need to query, update, or delete records based on non-trivial criteria? If so you may want a DB for the ability to express these criteria in SQL?
Or are there just big lists of a small number of types of things that are mostly independent of each other and that you'll just be accessing sequentially? If so, simple file system storage may be appropriate for you.