Some fun math: according to some estimates there is 175 zettabytes of data worldwide. Assuming 20-terabyte harddrives, this could be stored on 8.8 billion drive

Some fun math: according to some estimates there is 175 zettabytes of data worldwide. Assuming 20-terabyte harddrives, this could be stored on 8.8 billion drives. Assuming 10 drives per rack unit, 42 RU per rack cabinet, 16 square feet per cabinet (including aisle space), that means you need about 330 million square feet of data center space to host this data. If it was hosted in a single square data center, it would be 3.5 miles long and wide. (I always like to picture the physical space something would occupy.) And energy wise, assuming 5 watts per drive, it would consume 44 gigawatt, so it could be powered by about two large hydro dams similar to the Three Gorges Dam (22 gigawatts capacity). I am assuming a PUE close to 1.0 for simplicity. Of course one would not be able to spin up all these drives at once, since a drive spinning up consumes about three times more power (15 watts). So you would definitely staggered spin up when booting the servers :-) If 90% of this data is "crap" and could be cut down, it would still be just a drop in the bucket compared to worldwide energy use.