Both have advantages and disadvantages
Database
1. You need to convert to binary and store and then again convert
2. Increases database size
3. User cannot view file on server directly thus an added security
4. Can be slower process to get it back from database
Disk
1. I recommend to store files in folder and their path in database
2. Easy to implement and does not increase database size
3. No conversion process
4. Will be faster
5. User accessing server can view files, so if not secure you can use it