Technology's Promise - Chapter 4

The more I re-read the chapters of Halal's book, the less I like it. I was reviewing Chapter 4 again when I came upon this comment: "Turner Entertainment is using holography to store 1.6 terabytes of movies and video".

This caused me to make several comments. First of all several terabytes of anything is pretty small potatoes these days. Both HP and EMC have mid-range storage systems in the multi-terabyte range and some of HP's customers have over a hundred of these systems and that's just to store relatively small bits of information such as shopping accounts and junk mail. When we look at the storage required for (say) an on-demand video system we come up with pretty big numbers. We can do a back of an envelope calculation. Let's say a DVD holds about 5 GB and that's about what we need for one movie. According to IMDB.com there are about 700,000 movies in existence today in one form or another. If we made DVDs from all of them we'd need 700,000 DVDs (duh) or about 3,500,000 GB of storage. That's 3,500 terabytes - or about 2,000 times as much as Halal says Turner is storing with holography.

In a Computerworld article in 2005 (http://www.computerworld.com/hardwaretopics/storage/story/0,10801,106288,00.html) Turner was apparently considering using holographic storage - although none of the articles I read described the technology in any detail. This move was apparently to get away from magnetic disk storage. But why would you do that unless you only want to archive the movies? Using a medium that does not have random access (CDs and DVDs are essentially serial devices) means you cannot easily stream movies to multiple users where each user is at a different place in the movie - and this is exactly what we need for on-demand movie watching. Magnetic disk storage is cheap and capacities continue to increase every year making it cheaper and cheaper to store data on them. High speed (10K RPM) fibre-channel SCSI disks that form the core of modern storage systems are also very reliable. When you add a redundant controller system with a few GB of cache memory you have a very cheap (relatively speaking) way to store petabytes or even exabytes of data and still have very fast random access.

So the thing I really dislike about Halal's statement is that it's a throw-away catch phrase intended to establish some sort of "wow that's cool" feeling in the reader - but only if the reader is ignorant of the current state of technology. This is the essence of selling snake oil.

Nigel