What medium should be used for long term, high volume, data storage (archival)?

Problem

This question was inspired by https://superuser.com/questions/374386/how-to-store-and-preserve-lots-of-data. There have been other similar questions, but none with the same criteria. This is two questions in one. How do you store financial/critical records that should survive anything but a fire and should be available for decades? Lets say I want to store family photos/videos and want people do be able to find them in storage 100 years from now and still be able to use them. How would this be done? Criteria Long term means 30+ years guaranteed. 100+ years average. [If this is not practical, use the closest solution] High volume means a couple terabytes. Answers can be 'no-compromise/industrial' solutions or practical solutions for the home office/small business user. Media will not be active during the timespan. (i.e., if you suggest hard drives, they will not be spinning). Further, there is no expectation of needing to read these archives. They are there for emergency or "for future…