Helium-Filled Hard Drives Lift Performance

Due to its lower density, helium has long been considered an ideal medium for the innards of a hard drive. It stays cooler and allows the platters to be closer together because of reduced turbulence. Low density, however, is a double-edged sword because helium leaks easily. Drive maker HGST claims to have eliminated that problem.

Storage manufacturer HGST, a division of Western Digital on Thursday demonstrated a helium-filled hard drive enclosure.

This platform will let HGST design seven-platter drives in a standard 3.5-inch form factor. The company currently has five-platter drives in that form factor.

With the added capacity two more platters offer, a helium-filled enclosure will improve the total cost  of ownership of such a device in various areas, HGST said.

"It is extremely difficult technically for an air-based drive to achieve the same capacity points that we can achieve with helium," Brendan Collins, HGST's vice president of marketing, told TechNewsWorld.

"Longer term, this allows our higher-capacity drives, based on helium, to provide a lower cost per GB," Collins continued.

HGST's Helium Enclosures

The helium-filled enclosures will be available in 2013, but Collins declined to specify exactly when. He also declined to discuss specific product parameters or future plans when asked.

However, Collins did say that the helium sealed enclosures will carry HGST's standard enterprise-class 5-year warranty and two-million-hour mean time between failure (MTBF) specifications.

Helium-filled enclosures "cost more to make, and these costs have to be passed on to buyers to make this kind of effort financially viable," Rob Enderle, principal analyst at the Enderle Group, told TechNewsWorld.

Such enclosures "will likely be considerably higher-priced" than standard enclosures, Enderle suggested.

Why Helium?

The storage industry has been laboring for decades to figure out a way to create enclosures filled with helium instead of good old air.

"The HDD industry has been trying to develop solutions for the last 10-plus years," HGST's Collins said. "However they have not been successful in finding solutions that manage leakage and to cost effectively manufacture millions of these drives on a quarterly basis."

Storage manufacturers are interested in helium because has a lower density and higher thermal conductivity than air. That has several benefits.

A comparison of two commercial hard disk enclosures, one filled with helium and the other with air, found that the first was 41 percent cooler than the second,researchers have found. Further, the researchers projected that spindles in helium-filled enclosures can spin at up to 19,000 rpm, compared to the 15,000 rpm maximum in air-filled enclosures. This would increase data access rates by 25 percent.

Further, helium's lower density means much lower turbulence. The flow over a 70 mm disk may be turbulent for speeds over 2,000 rpm in air, but, in helium, speeds will have to exceed 15,000 rpm before turbulence becomes a problem, according to this white paper from Xyratex.

Other Gas Pains

Turbulence leads to track misregistration (TMR), which basically means the disk's head read or head write gaps aren't where they should be.

That's a limiting factor in storage enclosure capacity. "Current air-based 5-disk designs, including our own, will bottom out due to the track mis-registration issues caused by air turbulence," HGST's Collins said. "This industry problem is greatly reduced with helium."

Other problems that had to be solved include how to keep the helium in an enclosure and the air out.

"Helium is a very difficult gas to contain," Collins said. "A big focus in our development of this technology has been to make sure we don't have any leakage issues. We have implemented unique features into our manufacturing and test process to assure the quality."

However, Collins wouldn't say how HGST did this, citing "competitive and proprietary reasons."

No Mas Gas?

There's reportedly a looming shortage of helium worldwide, and this has been attributed to two factors -- years of low market prices, which discouraged the production of the gas, and the privatization of the United States federal helium reserve program.

This has driven up helium prices.

"We are not concerned [about the shortage] due to the small amount of helium usage per drive," HGST's Collins said.

In any event, drive manufacturers "can afford to pay more for helium than most existing users of this gas, and should therefore be able to get what they need," Enderle pointed out.