http://what-if.xkcd.com/imgs/a/31/fedex_drives.png

When – if ever – will the bandwidth of the Internet surpass that of FedEx?

—Johan Öbrink

Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

—Andrew Tanenbaum, 1981

2040.

If you want to transfer a few hundred gigabytes of data, it’s generally faster to FedEx a hard drive than to send the files over the internet. This isn’t a new idea—it’s often dubbed SneakerNet—and it’s how Google transfers large amounts of data internally.

But will it always be faster?

Cisco estimates that total internet traffic currently averages 167 terabits per second. FedEx has a fleet of 654 aircraft with a lift capacity of 26.5 million pounds daily. A solid-state laptop drive weighs about 78 grams and can hold up to a terabyte.

That means FedEx is capable of transferring 150 exabytes of data per day, or 14 petabits per second—almost a hundred times the current throughput of the internet.

If you don’t care about cost, this ten-kilogram shoebox can hold a lot of internet

We can improve the data density even further by using MicroSD cards:

Those thumbnail-sized flakes have a storage density of up to 160 terabytes per kilogram, which means a FedEx fleet loaded with MicroSD cards could transfer about 177 petabits per second, or two zettabytes per day—a thousand times the internet’s current traffic level. (The infrastructure would be interesting—Google would need to build huge warehouses to hold a massive card-processing operation.)

Cisco estimates internet traffic is growing at about 29% annually. At that rate, we’d hit the FedEx point in 2040. Of course, the amount of data we can fit on a drive will have gone up by then, too. The only way to actually reach the FedEx point is if transfer rates grow much faster than storage rates. In an intuitive sense, this seems unlikely, since storage and transfer are fundamentally linked—all that data is coming from somewhere and going somewhere—but there’s no way to  predict usage patterns for sure.

While FedEx is big enough to keep up with the next few decades of actual usage, there’s no technological reason we can’t build a connection that beats them on bandwidth. There are experimental fiber clusters that can handle over a petabit per second. A cluster of 200 of those would beat FedEx.

If you recruited the entire US freight industry to move SD cards for you, the throughput would be on the order of 500 exabits—half a zettabit—per second. To match that transfer rate digitally, you’d need take half a million of those petabit cables.

So the bottom line is that for raw bandwidth, the internet will probably never beat SneakerNet. Of course, the virtually infinite bandwidth would come at the cost of 80,000,000-millisecond ping times.

via What If? http://what-if.xkcd.com/31/