Toshiba Achieves Record Areal Density in 2.5-Inch HDDs

Toshiba announced a significant breakthrough in HDD density, as it eclipsed the one terabit per square inch (1Tbit/in²) threshold. Surpassing this threshold in a shipping drive is a first in the HDD industry, and surprisingly, Toshiba accomplished the feat with standard PMR (Perpendicular Magnetic Recording) technology.

The HDDs that power our lives overwhelmingly leverage the tried-and-true PMR recording technique. PMR made its debut in shipping products in 2005, which is quite a while ago when measured in tech years. PMR aligns data bits vertically on the surface of the HDD platter, which provides a big density increase over the previous technology. Unfortunately, PMR has limitations. HDD manufacturers have continued to refine PMR to extract amazing storage density, but until now the end of PMR appeared nigh.

A new recording technique is already on the market, and other technologies are waiting in the wings to move beyond PMR. SMR (Shingled Magnetic Recording) HDDs are already shipping. These drives achieve higher density by overlapping data tracks, much like the shingles on a roof. The only negative aspect is that SMR reduces performance, particularly when writing data.

Beyond SMR, there's HAMR (Heat-Assisted Magnetic Recording) on the horizon. This method uses lasers (yes, lasers) to heat a 20nm patch of the HDD's platter before writing data to it, if only for a brief millisecond. This increases density exponentially, and upper boundaries of HAMR will reach 5Tbit/in².

HAMR-equipped drives are projected to hit the market in 2016, but they'll debut with significantly lower density than the upper limit. BPM (Bit-Patterned Media) utilizes nano-lithography for amazing densities and is already in the experimental phase, but we do not expect that to come out of the lab for at least five years.

In the interim, we have PMR and its previous limitation of 800-900 Gbit/in² to tide us over. Toshiba's move to 1 Tbit/in² will increase the current density up to 750 GB per platter on 2.5" drives. A 40 percent increase in density in one hop is particularly impressive; the recent trend has been a 15 percent increase per year. This means a 3 TB 2.5" HDD will be spinning its way into your laptop soon, and possibly 8-10 TB 3.5" HDDs for desktop computers.

HAMR and other future technologies will likely come at a higher price initially, as manufacturers look to recoup the billions of dollars in research and development. In contrast, PMR's sudden new lease on life could work to lower the price of existing HDDs even further. Toshiba expects to begin shipping the new 2.5" products this year. This will extend the HDD capacity and price advantage, at least for the time being. 

Update, 1:15pm PST, 2/24/15: Toshiba quoted its increase as 40 percent, not 33 percent. We have fixed the error, and also changed an incorrect listing of 'Tbit/in²' to 'Gbit/in²'

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