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

Every now and then, comes along a quote which has unforgettable effect on you. The title of this note, is one such quote.

I remember sitting in the lecture room in 2005 at NCST and listening Prof Satam talking about computer networks. Like many other students, we just gaped at the slides on display one after the other and then suddenly in the middle of a saturday afternoon, this hits me. At that time of seeing the slides and the ensuing discussion, I was kinda PPMA (Physically Present but Mentally Absent) with all the numbers and bytes thrown in random going way above than Malcom Marshall’s bouncers. Its only later on, when I read the textbook “Computer Networks” by Andrew S Tanenbaums, did the profoundness of the quote dwelt on me. The wisdom propagated by the author, has had a deep impact on my psyche.

It spelt out the truth that we must always carry when we devise solutions for all kinds of problems. Common Sense is the vital key ingredient that all solutions must have. As technology professionals, there is a perceptible enthusiasm to incorporate newer technology as well as that sizzle that makes it sound like the state of the art cutting edge solution. Often, we get carried away to have that technological solution delivery to our achievements in our kitty when simpler solutions can be found with some plain thinking common sense.

That truth stuck on till date and everytime, I am required to devise a solution, the first thing that hits me is this quote. It forces me to adopt common sense as a platform and not get swept away by technological exuberances.

A brief explanation for folks who are from a non-techie domains:

Suppose you have a large data set that needs to be transferred from one location to another. The technology guy will rattle off statistic like you will need a 8 Mbps leased line and the transfer will take some days to finish ASSUMING the line does not drop etc etc. But with a little common sense, lot more can be achieved with far less too..

This is an excerpt from Tanenbaums book in 1990s; Picture yourself there as you read it..

…. A simple calculation will make this point clear. An industry standard Ultrium tape can hold 200 gigabytes. A box 60 x 60 x 60 cm can hold about 1000 of these tapes, for a total capacity of 200 terabytes, or 1600 terabits (1.6 petabits). A box of tapes can be delivered anywhere in the United States in 24 hours by Federal Express and other companies. The effective bandwidth of this transmission is 1600 terabits/86,400 sec, or 19Gbps. If the destination is only an hour away by road, the bandwidth is increased to over 400Gbps. No computer network can even approach this.

For a bank with many gigabytes of data to be backed up daily on a second machine (so the bank can continue to function even in the face of a major flood or earthquake), it is likely that no other transmission technology can even begin to approach magnetic tape for performance. Of course, networks are getting faster, but tape densities are increasing, too.

If we now look at cost, we get a similar picture. The cost of an Ultrium tape is around $40 when bought in bulk. A tape can be reused at least ten times, so the tape cost is maybe $4000 per box per usage. Add to this another $1000 for shipping (probably much less), and we have a cost of roughly $5000 to ship 200TB. This amounts to shipping a gigabyte for under 3 cents. No network can beat that.

The moral of the story is:

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


Posted on June 11, 2010, in Info, Uncategorized, Useful and tagged , . Bookmark the permalink. 1 Comment.

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