Seagate is now shipping its 10TB helium-filled hard drive in volume, and it’s hit this target without using performance-penalizing technologies like SMR (Shingled Magnetic Recording). While early high-capacity drives used SMR (a technology in which part of each track is overlaid atop the other, resembling shingles), it penalizes drive writes compared with non-shingled perpendicular recording. SMR boosts densities, but it hurts read performance, and more recent drives from all vendors have moved back towards conventional perpendicular recording.
Helium-sealed hard drives have been gradually making their way into data centers and enterprise drives. At 10TB, Seagate is pushing the envelope on absolute drive capacity as well, with seven drive platters and 14 heads in total.
This slide is from an HGST presentation, not Seagate, but it illustrates why drive manufacturers have moved to helium as one method of improving enterprise HDDs. By cutting resistance, they can stack more platters in a given space, thereby increasing drive density. The decreased resistance can also cut power consumption; Seagate reports that helium HDDs can use as much as 2W less power per drive than conventional HDDs. 2W might not sound like much, but if you’ve got an array of several thousand drives, cutting power consumption by 2W is a significant amount of savings that also reduces data center cooling load.
Part of what’s driving this shift to helium across the enterprise industry is the continuing advance of solid state drives, or SSDs. While enterprise SSDs have been fairly common across the industry for a number of years, concerns about reliability and price ensured that conventional hard drives continued to power the overall market. Decreasing costs and the advent of technologies like 3D NAND have allowed companies like Samsung to move back to older 40nm process technology with superior reliability and overall performance. In short, 3D NAND / V-NAND can be used to create more reliable SSDs that perform better over the long term.
While it’s true there’s still a sizable gap between SSDs and HDDs in cost-per-GB, that gap has been shrinking dramatically in recent years. 1TB SSDs can be had for as little as $219. The enterprise-class SSDs that would compete with similar products from HGST and Seagate are vastly more expensive, in both absolute cost and cost-per-GB — but enterprise hard drives aren’t exactly known for being inexpensive, either. List price for a 6TB helium drive from HGST is currently ~$500, or double the price for a consumer 6TB drive.
Pushing drive capacities upwards is one way enterprise manufacturers can continue to counter encroaching SSDs. Helium drive tech is one capability that’s not expected to come to the mass market — the drives are too difficult to manufacture to easily scale the technology to the cutthroat world of budget hard drives.
April 29, 2016