It has been some time, over seven years, since I compared mass storage costs. It would have been nice had I kept it up annually so that I would have interim prices but having looked at the pricing today, I don't think it would have mattered. Now, with SSDs becoming much more accessible and desirable to the consumer market, it is time for another look.

In my last article on the subject I noted that a friend claimed that SSD was the wave of the future and would replace rotating mass memory in five years. We're seven years down stream and Seagate has not yet filed for bankruptcy, so that prediction was a tad off. While I think SSD's advantages make it hugely attractive and that it or another solid-state technology (DNA?) will replace rotating memory someday, it's taking longer than my friend predicted.

Intense demand for solid state storage systems is keeping SSD prices high. Note in the table below that RAM has actually increased in price; I show DDR3 RAM but DDR4 costs slightly more. That demand will not abate, which means SSD can continue to command a price advantage for some time to come.

Let's see what we can glean from a seven-year perspective.

The last column, "HD Advantage," shows how much less a conventional hard drive costs compared to an SSD. This, to me, is the most telling calculation.

Moore's law implies that we should expect something to halve (price) or double (capacity) every 18 months. That's not reflected in the HD advantage. Even though the price of SSD dropped by a factor of about four, HD pricing dropped by a factor of three. SSD is gaining, but much more slowly than my friend predicted.

What do I think will happen, and when?

The hard drive has enjoyed a remarkably resilient market. While it appears the cost per GB is slowing at half or less of its previous rate, there will come a point where the vastly more complicated task of building a mechanical device with moving parts simply can't be squeezed any further. You'll be paying more for the enclosure and its parts that the medium itself. That said, one advantage enjoyed by hard drives is vast capacity. My dual 3TB drives are four years old and were not horribly expensive when I bought them. Seagate's current 8TB Barracuda drive is $200 or 3¢/GB, giving it a 10x HD advantage today.

Because of demand, I believe we will live in a hybrid environment for quite some time. My four-year old PC has a 256GB SSD as the boot drive and the 3TB HD mirror for bulk storage. If I was duplicating my PC today I would pay the same amount for double the capacity of both types. It's a very good way to balance the difference in cost between the two technologies while taking advantage of each's benefits.

Will my friend be right in another five years? No. Ten? Maybe. But I'll stand by my ending from the previous article - perhaps I'll live to see the demise of the mechanical, rotating hard drive, but don't count on it.

Note: I generally check prices on 3.5" 7200 Seagate Barracuda hard drives, SanDisk SDHC Class 10 memory cards, Intel's SSD products and Crucial's RAM products.