Question: how much gb is 4k video?
Answer: A single minute of ProRes UHD file (3840 x 2160) is around 5.3 GB (880 Mbits/s). You would need to expand your storage definitely if you are shooting at such high data rates. A single hour of 4K footage is a whopping 318 GB. 25 hours of 4K ProRes equals roughly 7.76 TB.