Just geometrically, tape will be king for ... quite some time. Imagine a HDD platter. You can only write to the surface of it. That's a small surface area, w

Just geometrically, tape will be king for ... quite some time. Imagine a HDD platter. You can only write to the surface of it. That's a small surface area, when you think about it. Now imagine the surface area of an unspooled tape ... Of course, SSDs are a different beast but they are nowhere near as dense. The spooling and unspooling for the geometric advantage is a tradeoff between time and space. Therefore, tape will continue to reign supreme for colder backup up until such time as some kind of holographic, volume-penetrating technique reaches the sheer density of a wound tape, adjusted by some kind of time factor for the read-write of our hypothetical holocube.