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New Seagate 6TB HDD renews debate about helium-filled drives

Are helium-filled hard drives the answer to the evolving cloud storage requirements of enterprises? Last year, HGST unveiled the 6TB Ultrastar He⁶, its first HDD that successfully used helium to increase capacity. Helium is less dense than air, and as such, it reduces the amount of resistance and heat inside the drive, meaning that spinning disks can operate with reduced friction and energy usage.

Accordingly, a standard 3.5-inch HDD filled with helium can accommodate seven platters rather than five, dramatically raising the ceiling for storage capacity and reducing the weight to data ratio by 30 percent. At the time of its release, the Ul​trastar He⁶ had 50 percent more space than cutting-edge 4TB HDDs. Plus, HGST stated that its product used 23 percent less power and was 38 percent lighter than air-filled drives. Helium-filled drives are also sealed (to prevent gas leakage), letting them be liquid-cooled safely, unlike standard HDDs that cannot be submerged without risk of damage to the disks.

Seagate unveils 6TB HDD that does not use helium
Despite its potential, helium is not unique in enabling capacity and performance gains. This week, Seagate announced a 6TB drive, touted as its fastest HDD ever. The Enterprise Capacity 3.5 HDD v4 is available with either 6 Gbps or 12 Gbps SAS connectivity. It does not use helium, however, although Seagate marketing manager Barbara Craig stated that the company would use helium "when we need it."

The drive can support up 550TB of data writes per year. For comparison, Seagate's current best-of-class desktop HDDs can sustain 55TB annually. Self-encryption and Super Parity error correction make these new high-capacity disks especially suitable for enterprise cloud storage applications.

"This is the fastest-growing segment in the enterprise space," said Craig. "People today are still trying to use desktop drives for near-line storage applications."

With Seagate demonstrating that 6TB of space can be achieved without helium, what's next for helium-filled HDDs? For now, these drives are the exclusive province of enterprises with ample budgets, although adoption and usage may rise as prices fall and technology is refined. Still, manufacturing HDDs with helium is a relatively new and technically challenging process. Moreover, helium is in limited supply worldwide, with only a few sites in the U.S. accounting for a substantial portion of all production.

While helium may eventually become integral to revitalizing cloud storage hardware, it is worth keeping an eye on alternative technologies that also push the capacity envelope. Shingled magnetic recording and heat-assisted magnetic recording are examples of techniques that could supersede standard perpendicular magnetic recording and enable more spacious HDDs.

The challenges of using helium for data storage
Helium is expensive. The U.S. has 75 percent of the world's supply and prices have been inching up as the future of the primary source sites remains in flux, according to Popular Mechanics. In 1996, Congress moved to divest the federal government from helium production by 2013, with the expectation that private operations would pick up much of the slack. That has not happened, as facilities operated by the U.S. Bureau of Land Management, under authorization from the Federal Helium Program, still account for 30 percent of the world's helium. The program's deadline was extended last September, but there is ongoing uncertainty about helium supplies.

The typical helium-filled HDD does not use all that much of the gas, anyway – maybe enough to fill a balloon. Still, the importance of helium to MRI systems, arc welding and microchip production has motivated some observers, such as Imperial College chemistry professor Tom Welton, to push for careful utilization of helium.

HGST's helium HDD was a breakthrough, and it shows how helium can enhance enterprise cloud storage media, even if other technologies can produce similar results. The question, then is whether the benefits afforded by helium outweigh the many challenges surrounding its usage, including its price versus air, leakage concerns and macro concerns about its supply. Seagate has explored helium in HDDs for a while now and has a number of patents related to its research, but it has so far held off on using helium for commercial solutions.

"Helium can solve some internal technical challenges, but it also creates new challenges, like how to prevent leaks and bring down manufacturing and materials costs," Seagate senior manager of corporate communications Jon Piazza told X-bit Labs. "Fortunately, we have been able to advance our drive technology and capacities without resorting to filling our drives with helium. We are also working on alternative technologies such as heat-assisted magnetic recording and shingled magnetic recording as potential ways to advance drive capacities in the future."

Alternatives to helium-filled HDDs
HDD technology has improved substantially in the last 60 years. For decades, manufacturers used longitudinal magnetic recording with horizontal layouts, until Seagate introduced PMR in 2002. This new vertical arrangement permitted much greater storage densities and gains in overall capacity.

Going forward, technologies such as SMR and HAMR could provide a huge leap over PMR and facilitate creation of enormous capacity drives that could rival the gains of helium-filled HDDs. SMR uses shingled layouts with tracks overlayed on each other, while HAMR utilizes a laser to heat the medium, making it easier to write to. To give an idea of how much capacity is enabled by techniques such as HAMR, consider that every book ever written could fit onto just 20 HAMR drives.

"The world is generating an astronomical amount of data annually and that data needs to be stored," stated Seagate CTO Mark Re. "We are approaching the limits of today's recording technology and with HAMR technology, Seagate is on track to continue to increase areal density delivering hard drives with the lowest cost per gigabyte and reaching capacities of 20TB by 2020." 

There have been significant improvements in commercial helium-filled HDDs over the last year, although only time will tell whether helium or technologies such as HAMR will lead the way in enabling the storage hardware that enterprises increasingly need. Seagate's new 6TB drive shows that there is still plenty to be done with air-filled media and that helium is not the only way to boost capacity and save energy when creating cloud storage systems.