Say your cable modem has a bandwidth of 1Mb/sec. That means you can receive one million bits every second, or 125,000 bytes per second (8 bits per byte). That's pretty fast. Is there anything faster ? Sure. Is there anything that's really faster - like multiple orders of magnitude faster? Yup. What about a Honda Pilot? Specifically, what's the bandwidth of a 2009 Honda Pilot where all of the 87 cu ft (150,336 cu inches) of cargo space has been filled with 1TB hard drives ?
A standard desktop hard drive these days is 4"x5.75"x1" , or 23" cu. So you can put 6,536 drives into your 2009 Honda Pilot - and still have room in the passenger seat for your lunch and a light jacket in case it's chilly when you get there. That's 6,536 terabytes (roughly 6 petabytes). And since bandwidth = data size / time, the effective bandwidth of your Honda Pilot depends on how fast you move those 6 petabytes.
Arrite... assuming you have 6 petabytes of data you need to transfer from Apex NC to Greensboro NC (70 miles, all highway), is it faster to do it by car or by cable modem ?
-
6,536 drives x 1012 bytes per drive = 6,536,000,000,000,000 bytes*
6,536,000,000,000,000 bytes / 125,000 bytes per second = 52,288,000,000 seconds
52,288,000,000 seconds = 871,466,666.66 minutes
= 14,524,444.44 hours
= 605,185.18 days
= 1,658 years
On your cable modem, it will take 1,658 years to transfer that much data.
A Honda Pilot can easily do that 70 miles (without being pulled-over for speeding) in an hour. And consider that upload rates on a cable modem are often capped at a fraction of the download rate; it could easily take four times longer to upload that data than it would to download it. Yet the Honda Pilot can do the drive in either direction just as quickly.
Of course this calculation happily ignores the time it takes to move all the HDDs in and out of the Pilot. And we've ignored the fact that these HDDs will easily weigh more than 5,000 pounds. But hey, take your time, make multiple trips - you've got time to spare. You could even wait a few years until 500GB DVDs become a reality and carry 20,000 TB at a time.
When you get right down to it, an hour's drive in the Pilot is faster than a 1Mbps cable modem for any amount of data larger than 500MB. If you fill up your camera's 1G SD card, it's quicker to drive the thing an hour, and then drive back, than it is to email all those pictures.
Ain't math fun...
One of my professors, way back in 89 or so, used an example like this to demonstrate bandwidth - except he used a 73 Ford station wagon filled with 1" magnetic tapes driving from Rochester to Buffalo vs. a T1 line. The station wagon won.
We did not calculate the bandwidth of an ejaculation.
----
* - Assume the HDD capacities are specified with decimal prefixes not binary prefixes, so 1TB = one trillion bytes = 1012, not 240 (1,099,511,627,776) bytes.