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In computing, Kryder's law states that hard drives (HD) are benefitting from an exponential increase in the density (bits per unit area) of information they are able to store. Kryder's Law is essentially Moore's Law for storage. This is true, although the numbers associated with Kryder's Law resulted from a misreading of a SciAm article and, as such, greatly overstate the true rate of growth. Kryder's Law states, incorrectly, that the density of information on hard drives has been doubling roughly every 13 months.
Kryder's law arose from a misreading of a Scientific American article which purportedly said HD capacity had increased 1000 fold every 10.5 years, which implies a 13-month average doubling time. This error was pointed out on http://www.mattscomputertrends.com/Kryder's.html, and on April 9th posted to Slashdot. The true growth rate appears to be much slower. The article actually states that hard drive capacity was 2000 bits/sq. inch in 1956, and 100 billion bits/sq. inch in 2005. Beginning from the 2000 bits/sq. inch in 1956 and progressing to the 100 billion bits/sq. inch found at the time of the article's publication (2005) is a 50 million fold increase, which implies a 23-month average doubling time during that period.
The ongoing increase in information density has resulted in an exponential decrease in the cost of computer disk drive storage capacity. This has enabled the commercial viability of consumer products that require large storage capacities, such as the Apple iPod digital music player, the TiVo personal video recorder, and Google's Gmail web-based email program.
This is also gradually but significantly altering how programmers think: in many programming tasks there is a time-space tradeoff, so as space becomes cheaper and cheaper relative to CPU cycles the appropriate choice about time versus space changes. For instance in database work it is now common practice to store precomputed views, transitive closures, and the like on disk in order to speed up queries; 20 years ago such profligate use of disk space would have been impractical.
The law is named after Mark Kryder, a Seagate Technology engineer who has been on the cutting edge of storage research.
Wikipedia impact upon spread of law
According to Matt's Computer Trends at http://www.mattscomputertrends.com/Kryder's.html, Kryder's Law was invented by Wikipedia and is not otherwise notable.
- "Kryder's Law probably wouldn't even exist if it weren't for Wikipedia. The only time "Kryder's Law" is mentioned anywhere on the googleable Internet apart from works derived from the Wikipedia article is in the headline of the Scientific American article, which was senationalised, like most headlines, to attract interest. It seems an editor has read the article and used it as inspiration to create the wikipedia entry. A second editor has then misquoted the article when including the 10.5 year figure. Wikipedia's strong reputation did the rest."
Future of Kryder's law
Access times haven't kept up with throughput increases which themselves haven't kept up with growth in storage capacity. The main way to increase either is to increase the number of read-write heads in a hard drive. Since flying heads are the most expensive component of hard drives, increasing their number per hard drive wouldn't help Kryder's law. Currently, the most promising way to increase access times and throughput are with some form of nonvolatile RAM or holographic technology.
Kryder's Law has not been true for the past three years (as of mid-2006), and the vice president of Seagate projects a future growth in disk density of 40% per year *, which is less than that predicted by Kryder's Law or Moore's Law.
See also
References
External links
- Behold the God Box - Less's Law and future implications of massive cheap hard disk storage
- Table of hard disk capacity over the past 25 years
Computer storage | Electronic design | Rules of thumb | Digital media | Digital Revolution | Eponymous laws | Futurology
"Kryder's law"