Seagate has demonstrated the first terabit-per-square-inch hard drive, almost doubling the areal density found in modern hard drives. Initially this will result in 6TB 3.5-inch desktop drives and 2TB 2.5-inch laptop drives, but eventually Seagate is promising up to 60TB and 20TB respectively.
To achieve such a huge leap in density, Seagate had to use a technology called heat-assisted magnetic recording (HAMR). Basically, the main issue that governs hard drive density is the size of each magnetic “bit.” These can only be made so small until the magnetism of nearby bits affects them. With HAMR, “high density” magnetic compounds that can withstand further miniaturization are used. The only problem is that these materials, such as iron platinum alloy or a sprinkling of table salt (really), are more stubborn when it comes to changing their magnetism (i.e. writing data) — but if you heat it first, that problem goes away.
HAMR, which was originally demonstrated by Fujitsu in 2006, adds a laser to the hard drive head. The head seeks as normal, but whenever it wants to write data the laser turns on (pictured below). Reading data is done in the conventional way. Just so you understand how small the magnetic bits are in a HAMR drive, one terabit per square inch equates to two million bits per linear inch; in other words, each site is just 12.7 nanometers long — or about a dozen atoms.
In theory, HAMR should allow for areal densities up to 10 terabits per square inch (magnetic bits just 1nm long!), and thus desktop hard drives in the 60TB range. Meanwhile, conventional perpendicular recording is expected to hit one terabit in the next few years, but the roadmap to greater densities isn’t very clear. There is no word on the cost of HAMR drives, or whether the addition of a laser will significantly impact power consumption or I/O performance.
The biggest winner from larger hard drives, of course, is cloud storage and computing — but then again, the other angle is that you’ll have so much local storage that the cloud seems a bit pointless, especially when we all have 100Mbps internet connections. But then again, with the unstoppable surge of smartphones and tablets and flash memory, do mechanical hard drives really have a future in consumer electronics?
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