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"  (Illustration by Loguy) Hard drives could reach their limits by 2015 unless researchers can find new ways to cram more information onto their disks. These drives use electrical pulses to create magnetic patterns on grains stored in rings on disks; when the disks spin, a scanner reads the patterns of electrical resistivity to retrieve the information. The storage capacity of the hard drive has risen from less than 0.1 gigabits (Gb) per square inch to over 100 Gb per square inch today. One breakthrough is &amp;quot;perpendicular recording,&amp;quot; which adds a bottom layer of magnetically weaker material to the disk, allowing it to store extra information. However, consumers&amp;#039; need for more space to store videos, commercial information and experimental data is outpacing hard-drive development, so designers are seeking new ways to satisfy this growing appetite.  A real density of HDD products vs. year of introduction. The rate of increase in a real density is slowing significantly. (Table by Journal of Magnetism and Materials, Future Hard Disk Drive Systems, Roger Wood) Three Ways to Deepen Disk Drive Storage 1. Laser Enhanced Heat-assisted magnetic recording uses a laser to heat a nanometer-size region on the disk at the moment when it is writing information. The heat enables the disk to cleanly store more information, and rapid cooling stabilizes the written data and reduces interference later.  2. Two-Dimensional Rings Disks currently store data in independent concentric tracks, wasting some space. Designers are looking for ways to overlap the rings and still read data. If the read/write head could identify patterns when adjacent tracks interact, and pluck the correct data from the interaction, the storage potential of a disk would be increased. 3. Bit-Patterning Magnetic grains could be stored in some organized way, such as in a series of 10-nanometer-wide magnetic islands etched into a disk by an electron beam. This would allow a much greater volume of information to be stored.   The structure and components within a hard disk drive. The electromechanical design has evolved into a model of simplicity and economy that has changed little over the past 20 years. (Diagram by Journal of Magnetism and Materials, Future Hard Disk Drive Systems, Roger Wood) "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/technology/a5464/4342559/>