David Berlind did this excellent interview with Wolfgang Gentzsch, who is one of the pioneers of grid technology,anddispels some of the myths of grid computing. In the past, I've tried to dispel some of the grid mystique myself but it's been a challenge to get the point across. Now, even Mr. Gentzsch makes it clear that the grand vision of a grid over the Internet is just a bunch of hype. He goes on to say that grid computing may have a role between organizationssuch as a hospital that leases high speed private lines to link with other hospitalsthatmay have idle CPU clock cycles to spare.Here's my question: The other hospital may have idle bed sheets, idle microwave ovens, idle beds, idle x-ray machines, and idle operating tables. Does that mean it makes sense to fly the patients and doctors around via private helicopters between the hospitals?
The first thing we should be clear about is that hospitals are not in need of greater processing power. Hospitals are mostly in need of better infrastructure such as wireless LANs, better software, better systems integration and implementation, and better security. Even if a hospital (or any organization) needed more computing power, it would be much cheaper to build a cheap super computer using commodity AMD- or Intel-based hardware than to pay through the nose for monthly OC3 service -- justas it isn't feasible to lease your own helicopter fleetin order to share some physical resources. Even if budget was no object, an OC3 circuit still has less than 1 percent of the throughput of the type of Cisco WDM optical gear mentioned in David's article, so it will be very limited to the types of grid applications that can be run. One of the biggest fallacies of the logic behind the "need" for grid computing is that processing power is somehow scarce and/or expensive. That couldn't be further from the truth because processors are dirt cheap. Building a bank of AMD- or Intel-based PCs into a super computer is, relatively, very cheap and very practical, not to mention that you have the luxury of cheap gigabit interconnects in the form of CAT5 or Multimode Fiber cables within the cluster. The bottom line is, the speed and cost of a localized cluster will always be an order of magnitude superior to a wide area cluster.
Finally, the biggest obstacleto grid computing -- which no one hasanswered convincingly -- is security. It's one thing to store or transmit encrypted content on an untrusted medium, and the solution is relatively simple and trivial. It is something else to process transactions on an untrusted processor; at some point, the data must be unencrypted before it can be processed. I have yet to see a grid that can take in encrypted data that it has no way of decrypting, process it, and then output encrypted data that only the source of the original job can decrypt.