Just what is the bandwidth of a van full of hard drives traveling 300 miles at a speed of 65 mph?

After a short Twitter discussion based on this post which suggested Ye Olde Sneakernet is the best way to transfer large data sets from the enterprise to the cloud (which is, unfortunately, not as uncommon a suggestion from cloud providers as you might think) I was dared to compute the actual bandwidth of said sneakernet (probably because I said I had the urge to do just that, but is that really important? I didn’t think so.)

I have a hard time passing up dares like that, but you knew that, didn’t you? So let’s get out our papers and dust off the old math textbooks, shall we?


HERE COMES THE MATH…

2008-dodge-grand-caravan-cargo-van-cargo-holdjpgOur van is a 2008 Dodge Caravan with an interior carrying capacity of 143.8 cubit feet. There are 1728 cubic inches in one cubic foot, which means a total of 248451 cubic inches are available for our hard drives. 

Our hard drives are Maxtor BlackArmor Portable hard drives, 160 GB each. Dimensions are: 5.17" H x 3.32" W x 0.67" L for a total of 11.5 cubic inches. Let’s say 12 cubic inches per drive, just to make the  calculations a little easier.

That means there are: 248451 / 12 = 20704 hard drives in the back of our van. That’s a total of 3,312,640 GB. 

Okay, that was the hard part. The rest should be fairly straightforward.

The van is traveling at 65 mph. We assume no congestion (traffic jams) for the purposes of this illustration.

It will take the van 4.6 hours to reach its destination, which means it takes 16560 seconds to arrive at “the cloud”. Given the amount of data we’re transferring, that means an effective transfer rate of: 200 Gbps.

That sounds pretty good, until you consider the latency incurred from a pit stop and I’m not sure there’s a way (yet) for application delivery to address that.

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