First of all, we have to differentiate between the two different types of storage devices.
The hard drive has come a long way since its invention in 1956. The IBM 350 Disk Storage was the first commercial hard drive and it stored less than 5 MB, which sounds ridiculously low compared to today’s terabyte disks. Then consider that the 305 RAMAC was based on 50 24-inch platters spinning at 1,200 RPM!
It took almost 30 years until hard drives were standardized using the ATA and SCSI interfaces, and until they reached affordable capacities in the two-digit megabyte range. Another decade passed until 3.5” drives were available at multiple gigabyte capacities. We selected an IBM Deskstar DTTA-351010 with 10.1 GB of capacity because it is one of the few old hard drives we have that is still fully operational, and because this is a capacity you’d typically choose for convenient storage media such as DVD recordables or flash-based thumb drives today.
However, hard drives still are the most controversial component in a PC, as they have increased their capacity to impressive levels without gaining in performance proportionally. We’ve had several articles that deal with hard drive characteristics in detail; they may help you understand hard drive performance better:
Flash Developed Much Faster
The development of flash memory has not only been quicker, but it has also been almost exponential, meaning that capacities have at least doubled every year. While flash has been used to store operating code for all sorts of devices such as the PC BIOSes and firmware for consumer devices, it has also been developed as a general-purpose storage medium for all types of applications.
While first-generation flash storage products typically offered only several megabytes of capacity and poky USB 1.1 performance, today’s flash-based USB thumb drives are often bottlenecked by the USB 2.0 interface. Capacities have increased to 64 GB. And 32 GB USB thumb drives are fairly affordable.
If flash capacities keep doubling every year, cheap flash-based storage devices will deliver more capacity than entry-level hard drives. Although capacity increases for hard drives will continue to be substantial, flash-based storage will increase in capacity more quickly. That said, reaching mainstream HDD capacity levels is way out of reach for the next few years.