I've been following this thread closely, and think a valuable exercise would be to create detailed cost models for different storage scenarios. Scenarios might include:
- Hard disk on a shelf - Optical media (gold CD-R, DVD-R, Blue Ray) - Managed storage (mirrored on-line storage, tape back-up)
Common to each storage scenario:
- Model three different size collections (1 TB, 10 TB, 50 TB) - Model a 50-year or 100-year life cycle - Make reasonable assumptions for media checking, refreshing, migration, and physical storage - Make assumptions about density and technology evolution (Moore's law-ish)
Maybe there are other storage scenarios to be considered, and other details to be considered, but you get the idea.