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Laser-Heated Hard Drives Could Break Data Density Barrier

Scientists at Seagate Technology show that heat-assisted magnetic recording could break the looming terabit-per-square-inch data limit

3 min read

24 March 2009—The density of data on hard-disk drives has doubled every three years since they were invented in 1955. Today’s hard disks pack 500 gigabits on a square inch (6.45 square centimeters). But magnetic disk recording as it is done now will run out of steam in just one more doubling, at 1 terabit. Engineers at Seagate Technology’s research arm, in Pittsburgh, have built a prototype heat-assisted magnetic recording scheme, which has the potential to allow up to 50 Tb per square inch.

Hard disks today are made of ferromagnetic materials, typically cobalt alloys. Bits are recorded as tiny magnetized regions of the material—the magnetic fields of all the grains in the area are aligned in one of two directions. As densities go up, bit sizes go down, reaching a few tens of nanometers across at 1 Tb per square inch. At those dimensions, the grains become unstable; a small amount of heat is enough to make them flip their magnetization direction.

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Why Functional Programming Should Be the Future of Software Development

It’s hard to learn, but your code will produce fewer nasty surprises

11 min read
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A plate of spaghetti made from code
Shira Inbar
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You’d expectthe longest and most costly phase in the lifecycle of a software product to be the initial development of the system, when all those great features are first imagined and then created. In fact, the hardest part comes later, during the maintenance phase. That’s when programmers pay the price for the shortcuts they took during development.

So why did they take shortcuts? Maybe they didn’t realize that they were cutting any corners. Only when their code was deployed and exercised by a lot of users did its hidden flaws come to light. And maybe the developers were rushed. Time-to-market pressures would almost guarantee that their software will contain more bugs than it would otherwise.

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