Helium-filled hard drives reduce friction and hence allow more storage with 20% less power
// November 5th, 2013 // Hardware
Helium, the 2nd lightest element, is already used in the cooling of superconducting magnets. Helium reduces friction, vibration, and heat and thus, when utilized in hard drive design, reduces mechanical issues that limit the storage density while using 20% less power than conventional hard drives. And it’s not a pipe dream either. Data-storage company HGST (a Western Digital company) has begun making a six-terabyte helium hard drive that has a 50 percent greater storage capacity and uses about 20 percent less power than conventional hard drives.
According to HGST:
“New up-and-coming helium-filled platforms are capable of supporting seven platters per standard 3.5-inch HDD, two more platters or disks than the current air-filled, five-platter drives. As a result of the helium filling, the seven-disk drives will deliver massive capacity while consuming 23 percent less power per drive, delivering 45 percent better power density and running four degrees Celsius cooler.”
Researchers have known about the benefits of helium-filled hard drives since the 1970’s but to date, keeping the leaky gas inside the housing has been technologically impossible due to its inherent “creeping effect”. When a surface extends past the level of helium, the helium moves along the surface, against the force of gravity. Helium will escape from a vessel that is not sealed by creeping along the sides until it reaches a warmer region where it evaporates. As a result of this creeping behavior and helium’s ability to leak rapidly through tiny openings, it is very difficult to confine liquid helium.
Given that helium-filled hard drives are built with very precise tolerances, if the helium gas leaks out, the hard drive dies. HGST however, using their new HelioSeal™ platform in its Ultrastar He6 HDD, has overcome the technological hurdles and is now producing hard drives guaranteed to last five years.
Technology Review explains how it works:
“Stacked inside a hard drive are magnetically patterned platters, each of which has an arm suspended over its surface. A read-write head hovers over the platter very close but without touching—about a nanometer away—using a magnetic field to read and write information. These tiny size scales and the high speeds of rotation (hard-drive disks spin at about 7,200 rpm) make hard-drive design very tricky.
As the platters in a hard drive start to move, the air surrounding the disk’s surface also begins to rotate. A hard-drive disk spinning in air meets resistance and tends to flutter, putting strain on the motor, requiring more power. Since helium flows better than air, drives filled with the gas experience very little friction, and the arms suffer less turbulence.”
“If the arm vibrates with even a nanometer amplitude, you’re toast,” says Hossein Haj-Hariri, a professor of mechanical engineering at the University of Virginia in Charlottesville, “Helium spills over and behind the arm, and the turbulence in helium decays rapidly.”
With helium lowering the levels of vibration and friction, there is less flutter and thus the platters can be made thinner allowing two additional platters to fit within the standard-size case. At 6TB, a low 5.3 idle watts, a reduced weight of 640g, and running at 4-5°C cooler, the new Ultrastar He6 lowers data center TCO on virtually every level. Key TCO benefits when compared to a 3.5-inch, five-platter, air-filled 4TB drive include:
- Highest Capacity HDD on the Market; 6TB, Seven-disk Design, Providing the Best TCO
- Lowest Power Consumption with Best Watts-per-TB
– 23 percent lower idle power per drive
– 49 percent better watts-per-TB
- Best Density Footprint in a Standard 3.5-inch Form Factor
– 50 percent higher capacity
- Lighter Weight than a Standard Five-disk 3.5-inch Drive
– 50g lighter even with two more disks, offering 50 percent more capacity
– 38 percent lower weight-per-TB
Sources: Technology Review, HGST, Wikipedia
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