Depends on how much data you care to store. I'm just trying to store family photos and what not, I'm not generating TB's a year. 100GB is more than enough for a whole year of important data for my family. A 25GB M-DISC BD-R, two to mail one off-site to another family member, and we've got an offline backup of our most important files with geo-redundancy. On top of the local copy and cloud storage whatever as well.