Flash vs. Hard Disk

Hard disk drives still have the edge over flash memory — but for how long?

For data storage, hard disk drives remain a better deal if you have a lot of data to store at a fixed location. Currently, you can get a 1-terabyte drive, the most efficient size as of right now, for about 10¢ per gigabyte. The cost of electricity, about $10 over the useful life of the drive, is not a determining factor.

By contrast, a 32-gigabyte flash drive, the efficient size in that medium, costs about $1 per gigabyte. As a form of storage, it is 10 time as expensive. But wait. Flash memory is not always more expensive. The least expensive hard disk drives cost twice as much as a 32-gigabyte flash drive, so flash memory is actually less expensive if that is all you need. There is, of course, a lot you can do in 32 gigabytes. The hard disk drive has the obvious price advantage currently for capacities of 100 gigabytes or more. The threshold for switching over from flash memory to hard disk, then, is somewhere between 32 and 100 gigabytes of total device storage.

This threshold is sure to move upward over time. Low-end hard disk drives are holding steady in price while capacity creeps upward. The low-end 320-gigabyte drive of 2012 may give way to the 500-gigabyte drive of 2013, but at about the same price. Meanwhile, flash memory prices seem certain to continue to decline, and capacity there too will increase.

This means we will find flash memory in more and larger devices, until eventually it becomes practical to make a desktop computer based on flash memory in place of a hard disk drive. Based on present trends, that changeover will happen between 2015 and 2021. Then hard disk drives will be found mainly in dedicated storage servers, and the whine of a hard disk spinning will no longer be the familiar sound heard in every office.

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