6TB Helium-Filled Hard Drives Take Flight 297
An anonymous reader writes in with some exciting news if you are a storage array manufacturer with a lot of money to spend on hard drives."HGST Monday announced that it's now shipping a helium-filled, 3.5-in hard disk drive with 50% more capacity than the current industry leading 4TB drives. The new drive uses 23% less power and is 38% lighter than the 4TB drives. Without changing the height, the new 6TB Ultrastar He6 enterprise-class hard drive crams seven disk platters into what was a five disk-platter, 4TB Ultrastar drive."
What the helium actually does (Score:5, Informative)
Here is a relevant portion FTA on what the helium actually DOES (unfortunately not mentioned in the summary):
At one-seventh the density of air, helium produces less drag on the moving components of a drive - the spinning disk platters and actuator arms -- which translates into less friction and lower operating temperatures.
The helium-drives run at four to five degrees cooler than today's 7200rpm drives, HGST stated.
Comment removed (Score:5, Informative)
10 Years of Research & unpressurised (Score:5, Informative)
They spent 10 years researching how to reliably seal it into an enclosure...
Also it is not under the same requirements of a compressed gas canister. The whole point of using helium is for the advantages of it's fluid dynamics compared to a normal air mixture, that's why it's not pressurised.
I've always wondered why they didn't just use a near vacuum enclosure, but i suppose it's much easier to not deal with pressure difference and use a super low resistance fluid instead at the same atmospheric pressure.
Re:What the helium actually does (Score:5, Informative)
This might help you... http://en.wikipedia.org/wiki/Flying_height [wikipedia.org]
Heads fly, and you don't "fly" in a vacuum.
Re:10 Years of Research & unpressurised (Score:5, Informative)
They don't work in vacuum.
Fluid interaction between spinning platter, gas and the heads creates an air bearing effect that holds the heads at a precisely determined (for a given linear velocity) height away from the disc. It's a stable system, so any slight vibration will be quickly compensated. Without a fluid filling, the heads would crash into the platter.
Re:10 Years of Research & unpressurised (Score:5, Informative)
I've always wondered why they didn't just use a near vacuum enclosure
Because the head would crash. The head does not just magically float a few micrometers above the disk platter. There is no way that any machine could be build so precisely. Instead of floating, it flies. The head is shaped like a tiny airfoil, and it use the ground effect of the air/helium/whatever to maintain the proper distance from the platter. This would not work in a vacuum.
Re:Great... (Score:2, Informative)
Re:Disks with helium? (Score:3, Informative)
If they're taking flight, then they used too much helium.
Re:Helium Leaks (Score:2, Informative)
You can get a REFURBISHED equal drive that has a higher chance of dying. Oh and the replacement has no warranty. The dark underbelly of hard drives is you get a single replacement, the replacement has a 90 day on it and that's it.
Re:10 Years of Research & unpressurised (Score:4, Informative)
They cant, hard drive absolutely rely on the Bernoulli principle to fly the heads, you have to have an atmosphere inside the drive for them to work.
Re:Helium Leaks (Score:5, Informative)
The dark underbelly of hard drives is you get a single replacement, the replacement has a 90 day on it and that's it.
Every Western Digital replacement drive I have received has had the longer of either the remaining original warranty or one year.
These are all drive in their "Black" line, so that might make a difference.
Re:Helium Leaks (Score:4, Informative)
Provided that atmospheric pressure works the fact that helium leaks is irrelevant: helium leaks into the harddrive just as easily as it leaks out of the harddrive. All you have to do is make sure that the harddrive is leak-tight for everything but helium - fortunately this is pretty easy to do as helium is the only gas that leaks as easily as it.
This is completely wrong. I assume you slept through your class on partial pressures. The helium would leak out until the concentration of helium inside equals the concentration of helium outside. The presence of other (non-leaking) gases is irrelevant. Since helium constitutes only 0.00052% of the atmosphere, that would result in a very high vacuum.
Re:Helium Leaks (Score:5, Informative)
You can get a REFURBISHED equal drive that has a higher chance of dying. Oh and the replacement has no warranty. The dark underbelly of hard drives is you get a single replacement, the replacement has a 90 day on it and that's it.
Not true. I had a seagate with a 5 year warranty go out 2 years into its life. The replacement had a 90 day warranty or what ever was left on the original warranty, which ever was greater.
Re:Great... (Score:5, Informative)
Which makes me wonder WHY He and not Xenon or another far easier to contain gas.
Xenon makes no sense whatsoever. It is heavier and infinitely more expensive than air. It is also a poor heat conductor, which is why it is sometimes used in sealed triple pane windows. It would be a terrible choice.
The point of using helium is that it is light, has low viscosity, high thermal conductivity, and is cheap enough to use in party balloons. Hydrogen is better on all these counts, but leaks more easily, can chemically react with some lubricants, and causes metals to become brittle. The only reason to even consider using any other heavier gas, would be if even helium leaked too much. But apparently they have that problem licked. So helium wins.
Re:Great... (Score:5, Informative)
This is not squandering, this is a good use and a great example of why we should not be squandering our helium reserves. And you could probably make a 100 drives for the amount of helium in 1 birthday balloon (the open space in a drive is a rather small percentage of the drive, which in turn is much smaller than a balloon).
Re:Great... (Score:5, Informative)
Not entirely true, hydrogen gas is pairs of hydrogens forming a molecule whereas helium is single atoms floating around making it much smaller and much harder to contain.
No, this is wrong. H2 is more permeable than He through almost any material. In particular, helium will not permeate through bulk metal that is carefully annealed to contain no microscopic cracks. Hydrogen, on the other hand, will slowly permeate directly through most (or maybe all?) bulk metals.
Re:Great... (Score:4, Informative)
What the hell does this have to do with money?
So you believe that in the future helium will be scarce but cheap? Or maybe plentiful but expensive?
Yes, it's theoretically possible to gouge future generations when Helium starts running out
Look, the US government maintained helium reserves for decades, and continuously lost money doing so. The reason is that we are NOT running out. There is plenty that is co-produced with natural gas, and there is plenty more in deeper deposits where it is naturally produced by alpha emission from radioactive substances, primarily thorium-232. In recent years the price of helium has gone up, but that is not because we are "running out", but the opposite: many of the Helium producing wells in Texas have been capped because they cannot compete with the price of shale gas. So more helium is staying in the ground.
History is full of chicken-little prognosticators that think they are smarter than the people actually willing to invest their money in their beliefs. If you really believe we are running out of helium, then you are free to invest your money in that belief. Someday you can sail your yacht pass all of us Pollyannas and say "I told you so."
Re:10 Years of Research & unpressurised (Score:5, Informative)
That's true for a regular hard drive, but I'm not sure that's true in this case.
e.g. A computer used at the ski resort in Mammoth Lakes experiences an air pressure about 25% less than sea level. So the volume of air inside the HDD enclosure wants to expand until it's 33% greater. With a regular HDD they just put in a filtered breathing hole to allow air in or out to equalize the pressure. This equalization is why the drive won't work in a near-vacuum.
If they'd filled this with helium, I can think of two ways they're handling this expansion problem. They're either using a bladder with regular air inside, and the breathing hole goes to the bladder. That's the way we handled the problem in submersibles - oil compresses slightly more than water, so if you simply seal your thruster motors in an oil bath, the water pressure will crush them and cause the rotating parts to bind. Instead, you attach the oil reservoir to a flexible oil-filled bladder exposed to water. The bladder shrinks under pressure, equalizing the oil pressure inside the motor with the water pressure outside, without contaminating the motor with water.
But since the HDD is bathed in a gas instead of a liquid, that wastes a lot of interior space - at least 33% if you want the drive to work at about 8000 ft, more if you want it to work higher. I'm not sure they have that much space available if they've crammed in 7 platters. So the other possibility is they've completely sealed the helium inside and the drive maintains the same internal pressure even at altitude.
Either way, there's a minimum pressure below which the inside of the drive won't drop. In the latter case the pressure is constant. In the former case the minimum pressure is simply the pressure when the bladder is completely emptied of outside air - i.e. even in a vacuum there will still be pressure inside the drive. And if they're having to do that anyway, they'd be smart to make sure that low pressure was still sufficient to allow the drive to operate. That would make this drive the only (relatively) cheap large-capacity drive capable of being used in low ambient pressure applications which normally have to use flash storage or an SSD.
Re:Nitrogen reacts with stuff? (Score:3, Informative)
When they talk about "nitrogen enriched" fuel they are talking about nitrogen compounds like NO2 and others - precisely because nitrogen *wants* to be N2, plus it's a good source of oxygen too. You absolutely want nitrogen compounds that are going to assist in the oxidation of those "energy rich" carbon chains, by bringing along oxygen and decomposing into N2 releasing gobs of energy.
It's why explosives work too - pack your compound full of nitrogen in such a way that it will stoichiometrically decompose into a miscellaneous product and nitrogen gas, then give it a kick and let that massive triple bond enthalpy do the work for you.
There's a reason high explosives are usually very high in nitrogen per unit mass.
No dishonesty in labeling, just a misunderstanding of the chemistry involved.
Re:Great... (Score:4, Informative)
" but leaks more easily"
No it does not. Helium is mono-atomic and has the smallest atomic radius of the mono-atomic gasses. This is why it leaks more than anything.
Hydrogen may be the smallest di-atomic molecule.
Re:What the hell is a helium bomb? (Score:3, Informative)
Most bombs become useless shortly after their first use anyway.
Re:10 Years of Research & unpressurised (Score:4, Informative)
Re:10 Years of Research & unpressurised (Score:5, Informative)
Very nice, insightful post, but not really what the parent posts were getting at. The original post that started the chain was something like "why don't they make the interior of the drive a vacuum rather than helium filled?" The answer was that the heads and the platters maintain proper distance using aerodynamic affects which wouldn't work if the drive were emptied of all air.
Re:The head never moves, the disk spins under it. (Score:5, Informative)
The head never moves, the disk spins under it. Putting a wing shape on the head wouldn't do anything.
It's too bad the disk doesn't drag some air along with it as it spins. If there was a layer of moving air along the boundary between the solid and gas, the heads could fly in that region.