Cheap secondary memory appears to cost around $0.03/GB in 2015. In the long run the price has declined by an order of magnitude roughly every 4.6 years. However the rate has declined so much that prices haven’t substantially dropped since 2011 (in 2015).
The price appears to have declined at an average rate of around an order of magnitude every five years in the long run, as illustrated in Figures 1 and 2. Figure 1 shows roughly six and a half orders of magnitude in the thirty years between 1985 and 2015, for around an order of magnitude every 4.6 years. Figure 2 shows thirteen orders of magnitude over the the sixty years between 1955 and 2015, for exactly the same rate. Both figures suggest the rate has been much slower in the past five years, seemingly as part of a longer term flattening. It appears that prices haven’t substantially dropped since 2011 (in 2015).
- John C. McCallum’s dataset includes a point at May 2015 for $0.0000317/MB, which is $0.03/GB. He says ‘In general, these are the lowest priced disk drives for which I could find prices at the time.’ Figure 1 shows a similar price, from a different dataset. We have not assessed how different the datasets are, however they look somewhat different.