Seagate Adopts Helium For a 10TB HDD (computerworld.com)

Lucas123 writes: Seagate has finally adopted helium as an inert gas in its data center drives and has used it to produce a 10TB HDD for cloud-based data centers. Seagate had relied on its shingled magnetic recording technology for high-capacity drives right up until its last 8TB HDD, even after WD has used helium in several iterations of its hermetically sealed, 3.5-in HDDs. The lighter-than-air helium reduces friction on platters and allows more to be used. In Seagate's new HDD, it crammed seven platters 14 heads, a 25% increase in disk density over its 8TB drive.

Comments

The helium will leak out, and drives will fai(#)&a

[viking80]

Worked for an measurement instrument company building instruments that had to work in helium atmosphere. We tried for a long time to seal the helium out. Even to the point of filling the entire inside with glass filled epoxy to prevent intrusions of helium. In the end we gave up, and did a redesign to work in helium. solid metal seals will work, but pretty much any other seal will not.

Re:Oh yeah!

[Doc Hopper]

> These drives will leak.

While technically correct, the rate of static-pressure helium leakage through HGST HelioSeal appears to be measured in decades. They up-rated their enterprise SAS drives from 1.4 million hours MTBF to 2.5 million hours MTBF because hermetically-sealing drives and using helium improves various operating parameters, prolonging life in several ways.

My results in production and the lab bear this out over the past two years: helium drives appear to have substantially lower failure rates than air-filled drives. While nobody has owned a commercial helium drive for a decade yet, the internal helium sensors on the disk farms that I've looked at show no degradation or leakage so far: SMART 22 shows 100.

I'll be watching Seagate's results here with great interest and optimism that their results parallel those of HGST.

Disclaimer: I'm an Oracle employee; my opinions do not necessarily reflect those of Oracle or its affiliates.

Re:Hydrogen next?

[hankwang]

The idea is that the thin film between the head and platter forms at a shorter distance in helium, so everything can be made smaller and closer together. As another poster pointed out, at room temperature/pressure, helium is monatomic while hydrogen forms H2 molecules, which are larger than the helium atoms.

What matters for the hydrodynamics (drag forces, lift forces on the head) is not directly the size of the molecule, but the molecular mass (related to densitiy of the gas) and the dynamic viscosity (related to both molecular mass and molecular size). The size of the molecule or atom is in any case vanishingly small compared to the distance between the head and the platter. The dynamic viscosities of a few gases at room temperature are: helium is 19 micro-Pa s, air 18 uPa s, and hydrogen 9 uPa s. The molecular masses (proportional to density) are 4, 29, and 2, respectively; this is where helium wins, but hydrogen is better both in molecular mass and viscosity.

The real reason for not using hydrogen gas is that hydrogen (H2) is reactive; at surfaces, it tends to split up into hydrogen atoms (H), which can then diffuse through metals and polymer seals. In the best case, it will leak out within months/years. In the worst case, it will change the crystal lattice and cause material failure. In particular, rare-earth magnents tend to crumble if exposed to hydrogen gas; that's something you really don't want inside a hard disk casing.