Although NAND flash memory is getting more and more popular among device manufacturers for performance, reliability and low power consumption, it will never completely substitute traditional hard drives, according to Steven Luczo, chief executive of Seagate Technology. NAND flash is too limited when it comes to supply and therefore can be a nice complimentary tech, but not the primary storage technology.

The demand for hard disk drive (HDD) storage was 400 exabytes (exabyte = one million terabytes) in 2011 and that number will increase towards one zettabyte sometime in 2015-2016 timeframe and then to seven zettabytes by 2020. According to Mr. Luczo, there are no capacities to build that volume of NAND flash memory in the world today and there will be no appropriate manufacturing capacities in several years down the road. As a result, the vast majority of data - including that on the cloud services - will still be located on hard disk drives.

"Flash is a complimentary technology, it is not a competitive technology. [...] Our industry shipped 100 exabytes of data five years ago, 400 exabytes in 2011, and we will probably ship a zettabyte sometime between 2015 and 2016. A zettabyte is equal to all the data that has been digitized from 1957 through 2010. [...] We are going to ship that in one year. So whatever the architecture is, pads, phones, notebooks, ultrabooks, real notebooks, PCs, servers, clouds, one year, a zettabyte – that is all going to be on rotating mass storage," said Steven Luczo, in an interview with Forbes web-site.

Since semiconductor manufacturing fabs are much more expensive than magnetic media factories and facilities that produce other HDD components, it is financially easier to increase total storage capacity required by the world using hard drive technology rather than using NAND flash.

"If you are trying to grow exabytes, what’s the capital investment to grow exabytes? For flash, it is $10 billion at a chunk, which is what it takes to build a new chip fab. For drives, it is a fraction of that. If the industry had to grow from 400 to 500 exabytes, we would do that on $1 billion of capital. [...] [To get to a zettabyte, we need] about $1 billion a year for us, and then about $1 billion a year for WD. Versus $50 billion [for NAND flash makers]," stressed chief executive officer of Seagate.

While NAND flash clearly cannot substitute hard disk drives in general, it very well fits into various tablets, notebooks and other mobile devices. Nonetheless, as the demands for storage space are growing at a rapid pace, Seagate believes that hybrid storage systems - which combine performance of NAND flash and capacities of HDDs - will make more sense than pure solid-state drives.