Disk To Flash

Yes, it's been a while since I've posted. My bad. Lots of travel in various permutations of business and pleasure and the organizational wreckage that comes from such. (Intel Developer Forum in San Francisco, hiking around Mt. Shasta and Point Reyes, Sun's "Galaxy" launch in NY, etc.) But I'm more or less dug out now.

To me, one of the more interesting aspects of the iPod nano announcement was that it's replacing the mini in Apple's product line--and thereby, in a single stroke, shifting a huge chunk of portable MP3 player volumes from disk to flash. (The iPod mini uses a hard disk while the nano uses flash memory.) Does this presage even more shifts from spinning steel to silicon?

The short answer is probably yes. The longer one is a bit more complicated.

Certainly it's hard to see the shift as anything but a complete one for many, many years to come. This post by Illuminata colleague Tom Deane gives some of the reasons. Price per bit is one big issue. Limited read/write cycles are another. Just as tape continues to exist alongside disks, disks will continue to exist alongside flash.

However, flash is well on its way to eclipsing disk for most really portable applications. Advantages like size, ruggedness, and lower power trump somewhat higher per-bit costs for the most part. The nano's a classic case study of the tradeoffs. Apple's taken the somewhat daring move of replacing its wildly popular mini with a device that's more expensive per capacity today. It's betting that the svelteness and longer batter life of the nano make up for giving up storage. One can reasonably argue with the timing; I would probably disagree, but it's a plausible argument that Apple could have waited until some price crossover point was reached. But there can be little dispute that flash continues to take over disk territory in these handheld (and smaller) devices.

That's because Moore's Law is outpacing usage models. Human hearing isn't getting better. We're not better able to watch movies on a small LCD screen. Useful digital photo resolution ahsn't plateaued yet but it's probably getting close. In other words, we're rapidly moving towards points where additional capacity in many types of devices becomes less and less important relative to other characteristics such as lightness of weight. As flash memories rapidly head into the multi-GB range, the size and number of MP3 files aren't increasing apace.

The replacement of disk by flash is one implication of these intersecting curves. Another is that silicon technology will increasingly not be a factor in how many functions can be crammed into a single device. Which isn't to say that everything will be. There are certainly user interface issues (which Apple can probably solve as well as anyone) as well as more subtle and less rationalist issues of style and brand.