It has been well over a year since my last digital storage update [3], and though there has not been any earthshaking new technology announced within that time, there has nevertheless been some advancement in several areas that I would like to address.
Vertical / Perpendicular Drives
One of the major highlights of the last year has been the introduction of so-called vertical or perpendicular drive technology. Vertical recording aligns the data bits in a vertical, or perpendicular, format with respect to the plane of the the storage media, instead of the traditional horizontal arrangement. Vertical techniques are already in use and have significantly increased storage densities, particularly for compact notebook drives (see Wired: Hard Drives Get Vertical Boost [4]).
New Media Manipulation Techniques
Working around the superparamagnetic limit by recording data perpendicular to the plane of the media is expected to peak at a data density of about 1TB per square inch. Seagate is looking to extend this gain by combining it with other technologies, to the extent that we could see data densities of 50TB per square inch within 10 years. A technique called HAMR (heat-assisted magnetic recording) uses lasers to heat up the disk surface while writing, which later cools to a more stable state. The heat expansion exposes fewer individual grains of disc material to the write process, thus increasing data density. This process is further refined by organizing the grains into a more regular pattern in a process balled bit patterning, where a chemically encoded molecular pattern is infused into the substrate during creation. The combination of these techniques with vertical recording yields a bit of data per grain of magnetic substrate, compared to about one bit per 50 grains that we see now (see Wired: Inside Seagate's R&D Labs [5]).
Hybrid Drives and Solid State Storage
While some manufacturers continue to push for higher data densities, others have improved devices in different ways. Hybrid drives have been developed that combine solid-state flash memory and conventional magnetic discs to increase speed and reliability. Though this development does little to increase storage capacities, it does help with reducing power consumption and portends the elimination of moving parts -- and the corresponding risk of mechanical failure -- as flash memory increases in capacity (see: PC Magazine: Seagate Launches First Hybrid Hard Drive [6]).
Speaking of Flash memory, Freescale has improved on the concept by introducing MRAM (magnetoresistive random-access memory). MRAM boasts faster read/write speeds and better stability than current Flash memory while still holding data after power has been removed from the chip. This technology improves on the upper limit of the lifespan of Flash memory (see: BBC: 'Magnetic memory' chip unveiled [7]).
As if MRAM and Flash are not enough, research is continuing on “phase change” memory that promises more stable storage than Flash memory at as much as 500 times the speed. In addition to faster and more stable storage, phase change chips promise to be much more compact. Initial prototypes of phase change chips have already been introduced by Samsung, and there will likely be production models out within a couple of years (see: Wall Street Journal: Disk Drives Face Challenge If New Chip Comes to Market [8]).
Again, these solid-state technologies do little to increase storage capacities, but improve stability and power consumption, and thus, offer more efficient and stable overall storage and retrieval systems.
Optical Storage
HD-DVD and Blu-Ray media are set to multiply their storage capacities by adding additional layers and increasing the data density per layer. At base specifications, 10 layers on an HD DVD would yield 150GB, assuming 15GB per layer. For Blu-ray, the total over 10 layers jumps to 250GB, assuming the base 25GB per layer. These extra layers are not supported by current readers, but the concept indicates a potentially longer lifespan for standards that initially seemed to be dead on arrival. (see: Daily Tech: Three HD Layers Today, Ten Tomorrow [9])
Meanwhile, much of the HD-DVD vs Blu-Ray debate has been thwarted by the announcement of a hybrid disc capable of storing data in both formats on one disc. Warner Brothers recently unveiled Total HD Disc, which eschews a standard format DVD layer in order to bundle the two competing HD formats into one disc playable in either type of HD player. This approach is contrasted by the introduction of dual players which have both HD-DVD and Blu-Ray capabilities (see: New York Times: New Disc May Sway DVD Wars [10]).
Even at the higher recording capacities imbued by multiple layers, neither standard will approach the capacities of the terabyte holographic discs that I reported on last year. Given the massive marketing effort behind HD-DVD and Blu-Ray, and the emphasis on applications in entertainment as opposed to mass storage, I have doubts over commercial manufacturers dumping these in favor of holographic media any time soon. The most likely effect of the market battles over the two dominant HD formats is that newer, higher capacity formats will come at a premium for those seeking to implement high capacity data storage solutions. Ars Technica suggests that smaller capacity formats will be exploited first in order to decrease the cost to end users and hasten adoption. But even such decreased capacities are expected to be greater than even the multi-layer HD-DVD and Blu-Ray concepts discussed above (see: Ars Technica: Holographic storage a reality before the end of the year [11]).
While the HD-DVD / Blu-Ray market squabbles continue, yet another terabyte optical technique has been developed. Research at the University of Central Florida developed a 3-D optical system that uses two different light wavelengths to write to multi-layer DVD media that promise more than a terabyte per disc. No plans yet on market potential, but with so many terabyte optical techniques, one or more are bound to arrive soon (see: University of Central Florida: UCF Researcher’s 3-D Digital Storage System Could Hold a Library on One Disc [12]).
Tape Scrolls On
Not to be outdone, new developments in tape technology promise 15 times greater data density in new cassette form factors within five years. This translates to roughly 8 TB per cartridge (see: SpaceMart: IBM breakthrough multiplies the amount of data that can be stored on tapes [13] and Wired: Tape Storage Increases 15 Times [14]). With this sort of density, tape still offers the best price to capacity ratio and still out-carries all storage media short of large magnetic disc arrays. The question of long-term reliability of tape is still debatable, however.
The X-Factor
Moving on to more theoretical realms, scientists at the Max Planck Institute have made a breakthrough on a 40 year old theory that reveals tiny, closed magnetic circuits -- vortexes -- that demonstrate polar properties that could represent data bits. This phenomenon occurs on a scale of about 20 atoms in diameter, which is much smaller than the single grains of magnetic material that Seagate hopes to exploit in the near future (see above). Techniques exploiting this phenomenon are expected to be much more resilient against external disruptions such as heat and magnetic fields, but no word yet on a horizon for practical application or storage densities (see: Max-Planck-Gesellschaft: Magnetic Needles turn Somersaults [15]).
Even further out there is a scheme proposed by a Drexel University professor that claims 12.8 Petabytes in the space of a cubic centimeter! The technique exploits the properties of nano-scale, ferromagnetic wires stabilized by water. Again, commercialization seems quite a ways away, but this should provide good fodder for speculative fiction writers everywhere, at least until the shock of a Petabyte iPod Nano wears off (see: Drexel University: For a Bigger Computer Hard-drive, Just Add Water [16]).
