What's the shooting ratio and total amount of dailies expected? If editing at 4K, you can work in an "offline" type quality of DNxHR LB (low bandwidth). If you use that and 1/4 proxy for transcode, a 4K UHD file is exactly the same data rate and storage needs as DNxHD 36. If you don't work in proxy mode, then you need 4x the storage space for the same amount of footage.
Then do what Shane mentioned for calculating storage needs based on type of RAID being used.