The technical part of the day opened with Bill Cain, Western Digital’s Executive Director of Advanced Product Technology, discussing some fundamentals of hard drive technology.
Nanotech is an overused term that refers to everything up to and including exotic, self-replicating micromachines from science fiction. Perhaps that’s why Intel likes to refer to its technology as “nanoscale,” rather than nanotechnology.
Still, Cain made a strong case that hard drives are working examples of nanotech in action. Consider a few key facts:
- Hard drive heads maintain a height of 10 nanometers above the surface of the hard drive, even as the surface of the disk is spinning at 7,200 RPM. To put that in perspective, the outer track of the platter is moving at 75 miles per hour while the head floats 0.000000039 inches above the surface. Even a 5,400 RPM, 2.5 inch laptop drive has the outer track moving at roughly 40 miles per hour. As comparison, consider that a typical human hair is 50,000 nanometers thick.
- A magnetic domain on a PMR (perpendicular magnetic recording) surface is about 118nm x 20nm.
- The reader gap width—that is, the part of the head that reads the data off the drive—is less than 200nm wide.
- All the various layers—and there are many—that comprise the actual working chemistry of the hard drive coating (not including the actual platter) is about 100nm. Some of the actual deposition layers are 2 angstroms (0.2nm.)
Cain also brought up the whole issue of flash storage. Currently, flash hard drives are the darling of the technology literati, but Cain suggested that actual capacities of flash will take a long time to catch up with magnetic media—and in fact, the tradeoffs needed to increase capacity of flash memory may sacrifice performance to build a bigger flash bit bucket.
Meanwhile, disk densities are still going up, as well as performance. It’s well known that hard drive write performance considerably exceed that of flash memory, and hard drives have a longer working life.
Today, current hard drives are at about 250 gigabytes per square inch, which translates to a terabyte hard drive with four platters. Western Digital has demonstrated working densities up to 520 gigabytes per square inch. What’s fueling this hunger for increased data density and capacity are video and smaller form factor hard drives.
Late in the day Dr. Sining Mao, Vice President of Device Design and Technology, discussed the company’s efforts to push densities up to a terabit per square inch. That density is still a few years off, but Mao seemed confident that current drive technology, with some enhancements, could hit that capacity. Continued…