Crispy edges

March 23, 2007

If you’re like me a fan of the crispy edges of your brownie/cake. Get this‘s labyrinth to bake them in.


Isn’t this sheer genius?!

Matthew Gray, software engineer at Google constructed a program to extract place names and map coordinates from the books in Google Book Search and then plot that data as points onto a representation of our globe.

Our world

Pretty cool isn’t it? See you’re doing something original when you write a novel that takes place in the top of Africa or a travel guide for somewhere in the top middle of Russia or on one of our poles.

Check out this post in which Matthew Gray gives an interesting interpretation of the data when he plotted it in the fourth dimension (time).

On Techmeme the following entry caught my attention;

Moving a petabyte of data

Interested in the math I followed the link but the permalink appeared dead and looking for it on the blog gave me no results (strange because according to Techmeme the entry was 25 minutes old).

Not Found

My disappointment soon made room for a pleasant memory, I remembered a interesting example of the same mechanism applied to station wagons.

A few years ago I had an university course about computer networks in which one particular lecture spoke to my imagination. The lecture was about transmission media. The slides of the lecture where based on the book Computer Networks (Tanenbaum 2003) and they showed with a simple calculation that it can be both time- and money-efficient to transfer data between computers is by writing the data onto magnetic tape or other removable media and then physically transport the data to the destination machine, and read the data back in. This method might not sound so sophisticated or technically advanced but it proves cost-effective for applications that require high bandwidth and/or low costs per bit transported.

This is an excerpt from Tanenbaums book;

…. 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

Inspiring isn’t it? That was written in 2003. Networks speeds are of course still increasing in an attempt to end the “tyranny of geography” (other catchy phrase from the same book) and it probably won’t be long before my ability to beat modern commercial computer networks with my Fiat 127 and my LaCie 640GB harddisk (2 .8 Gbps when driving to my parents a half hour away) will be surpassed by the next generation of commercial computer networks. (And really at this point – although it’s possible – there’s no reason for me to buy a bigger harddisk or a faster car. :))

Of course bandwidth is hardly the only property of interest, I would hate to wait a half hour for first images to come in when I turned on my TV. But the story is a nice way of putting current network bandwidth achievements in perspective.

Update: Johnathan Schwartz entry is online again.