The file you are refering to is a system file from the Updates when you updated the UniStream OS - via UniLogic
File_System.tar.gz 505,730,000 Bytes 507.730 MegaBytes well with in the 4 GigaBytes Limit
That particular folder - UniStream Files - can be deleted once the UniStream has been updated to the New OS.
Is your program writing files to the Micro SD Card?
How Often? How large?
Into specific folders? Are you exceeding the number of files in the folder?