Good question. It's 100m images, but I haven't tried to find how large all of it is.
We downloaded a subset of 3 million images, which is apparently 379.77 GiB. So a linear extrapolation would be (100/3*379.77) = ~12,659 GiB for the full 100m images.
12TB really isn't too bad. It's massive, yes, but imagenet 21k is 1.2TB.
