A data transfer issue today reminded me of one of my favourite words.
I needed to transfer some files from the office in Huddersfield to home, in Leeds.
There are obviously many ways to do this. I could email the files, I could use Google Drive or Dropbox, or I could copy the files to a USB stick and use Sneakernet. The main determining factors are file size, data transfer speed and (for Dropbox at least) whether or not the receiving computer is turned on.
A long time ago I used to set students the task of working out the answer. At the time, my journey home was about 20 minutes, Dropbox was a glint in its creator’s eye, and home Internet connections downloaded at 200Kb/s on a good day. The answer was a surprisingly small amount of data. For anything much bigger than a 700Meg CD it was worth making the round trip home.
Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.
Andrew Tanenbaum (allegedly)
So what, I fell to wondering, is the answer now? The journey home now takes an hour. My home Internet (presumably connected to the exchange by damp string) will download at about 700Kb/s. I can write a 1.5GB file to a USB stick in less than a minute, and read it back virtually instantly. Uploading the file to Dropbox takes upwards of half an hour, but I can start the upload before I leave and it will finish before I get home. And my home PC is turned on, so it will start downloading the file as soon as it sees it. It should be there in an hour.
So, my current answer is still surprisingly small. Anything much above 2GB of files, and Sneakernet is the quickest way to get a file from Huddersfield to Leeds.
There is, of course, an RFC which explains the best way to transfer large amounts of data over distances.
Edit: I am indebted to the anonymous person who pointed out this proof that the bandwidth of the Internet will never exceed that of Sneakernet.