SMART 22 is a Gas, Gas, Gas

By | April 16th, 2015

Backblaze Helium Pod
We recently filled a Backblaze Storage Pod with 45 HGST Ultrastar® He8 hard drives. For the uninitiated, these are 8TB drives filled with Helium. The Helium, so says the literature, allows the drives to run cooler and quieter, and reduces power consumption.

When we wire up a new hard drive model into our infrastructure, one of the things we need to do is figure out which SMART attributes the drive reports since nearly every different drive model reports a slightly different set of attributes. Below are the first few SMART Attributes reported by one of the 8TB HGST drives:

Smart Attribute 22

The attribute highlighted in “red” is SMART 22, and we had never seen that one before. We researched this “Unknown_Attribute” and couldn’t find anything online so we asked the HGST folks. They responded by saying that attribute 22 is the status of the Helium in a drive. It is a pre-fail attribute that trips once the drive detects that the internal environment is out of specification. They did not share the amount of Helium in a given drive or the “trip points” related to the amount of Helium although there is a normalized threshold value of “25” listed.

We’ll be monitoring this Helium filled pod over the next several weeks and let you know how things go. In the mean time feel free to impress your colleagues with your new found SMART 22 knowledge and just for fun here are a handful of Helium facts…

  1. The atomic number of Helium is 2.
  2. Helium is the second-most abundant element in the universe, with Helium atoms making up 1/4 of the mass in the Universe, but it is much less common on Earth.
  3. Helium is so light that Earth’s gravity is not strong enough to hold on to it. When Helium atoms are released into the atmosphere, they rise until they escape into space.
  4. Helium exists in Earth’s atmosphere only because it is constantly resupplied from two sources – decay of radioactive elements on Earth, and cosmic rays, about 9% of which are high-energy Helium nuclei.
  5. The Helium we buy in cylinders is produced by the natural radioactive decay of radioactive elements in the earth’s crust – principally Thorium and Uranium.
  6. Current world production of Helium is over 30,000 metric tons a year. Helium has been accumulating for many millions of years in a few natural gas fields, therefore we can currently extract more each year than is being created by Uranium and Thorium decay.
  7. Helium is colorless, odorless, tasteless, non-toxic, and inert.
  8. Helium makes up 0.0005% of all the air we breathe!
  9. Inhaling helium temporarily changes the sound of a person’s voice. Though Helium is non-toxic, breathing it can result in asphyxiation due to oxygen deprivation.
  10. At temperatures close to absolute zero, Helium condenses to a liquid with amazing properties – the properties of a superfluid, flowing with zero friction up and over the walls of containers.


FYI, if the Helium drives don’t work out, we’ve got another use for the Helium.


Andy Klein

Andy Klein

Director of Product Marketing at Backblaze
Andy has 20+ years experience in technology marketing. He has shared his expertise in computer security and data backup at the Federal Trade Commission, Rootstech, RSA and over 100 other events. His current passion is to get everyone to back up their data before it's too late.
Category:  Backblaze Bits
  • OllieJones

    Sometimes projects “jump the shark.” In Backblaze’s case, the shark’s jumping you. You guys are great.

  • Joseph Ryan

    So I have not read all the comments, but by far, my favorite ‘trivia’ about helium relates to it’s major industrial use – no, not party balloons, though that’s close, but – in liquid form to help cool the conductors in the electro magnets used by MRI machines into the superconducting zone.

    Also the USA has (or did have) a strategic stockpile of helium but that is almost another subject.

  • moldor

    Interesting that they used Helium rather than Nitrogen – I wonder what the performance difference is ?

    • Alex Hausrath

      Helium has a thermal conductivity almost 6 times what nitrogen has – Helium is also less reactive than nitrogen, as it exists in a monatomic state (doesn’t even bond with itself) vs diatomic for nitrogen (nitrogen will form molecules with other atoms)

  • karl

    At least HGST have faith in these drives offering 5 years warranty. Sounds like a good investment. It would be interesting to test HGST’s claim on

    0.35% failure rate when data is available. However, Seagate data sheet reported your 3TB HDD failure rate of <1% ( )

  • So with this helium in the drive, and SMART 22, that means that the system is entirely sealed, right? No more “breathing” holes or anything like that to account for changes in atmospheric pressure, etc.

    I guess SMART 22 makes sense then, because if the helium starts leaking out of the sealed system, you have a break in the seal, which means probably that the drive has way overheated, has suffered shock of some type, or other trauma that broke the seal and let some helium out. In essence, it’s measuring internal barometric pressure, of a sort. Would work with any gas, I suppose, but presumably helium allows for better aerodynamics across the platters and the head? I have no idea.

    Or it’s a gimmick. Time will tell.

    • Yea, we’re curious to see how they will preform over time. Any new HDD technology is welcomed though! We want more density!

      • Wayne Phipps

        Is this just an experiment? One of your other posts said that 8tb drives were both not readily available or cost effective or has the situation changed?

        • We’re experimenting for now. We anticipate their prices will go down, but we’re constantly testing various types of drives. Often just to test whether or not the technology works in our server design. If it does and it becomes cost-efficient to buy them, we’ll do so!

      • Rick Peralta

        >We want more density!

        I proposed a higher density architecture to BackBlaze a while ago. It may have been too forward thinking. Packing many petabytes into a single rack may be too much.

        My best guess would be 4 PB today and 32 PB in a rack, by the time you could effectively field it. And maybe 2Kw per rack, plus 10 watts per gigabit of traffic.

    • A.

      You can have a sealed drive and still adjust for atmospheric pressure – just have a small membrane that can move to equalize pressure, but that still prevents the helium from leaving.

      • Seerak

        Thing is, helium being such a light and small monoatomic gas, it can diffuse through damn nearly anything that other gases couldn’t – especially such a membrane. So I’m not surprised that SMART 22 exists. The thing I’m wondering about is what HGST figures is the halflife for the loss of sufficient helium that the drive’s remaining operational life is short.

        • A.

          It would not diffuse as fast as it often does because it would not be under pressure. Under pressure, like you say, it diffuses very fast, but with no pressure it would not be too bad. In fact if too much diffuses the drive would be under negative pressure (because other gas could not diffuse back), so I suspect it would stop diffusing entirely at that point.

          I do wonder how they measure SMART 22. Helium sensor? Pressure sensor? Just time?

          • Rick Peralta

            Maybe a heuristic of viscosity. If there were a breech, it would show up as a change in friction. That could be derived from the platter power when is is at speed. Electrically, measuring the voltage drop someplace convenient, like at the power supply, seems practical.

          • Iain McClatchie

            Helium is used with no pressure at all as a leak detector. Somehow trace helium detectors are really cheap to make, and the stuff clears away from the work area very quickly as well.

            My experience was with trying to stop helium leaking through welded aluminum sheet metal, o-ring joints, o-ring screws, and gasketted joints. All four were a huge pain in the ass. Many times we talked about how, even though helium wasn’t leaking, air and water vapor probably couldn’t get through the same leak path, and so we were probably tight enough. We couldn’t find a good way to measure tight enough, so we stuck with the helium.

            I wonder if very tiny leak paths act as a kind of Maxwell’s Demon, letting helium out but not letting oxygen or nitrogen in, and thus driving the internal pressure below that of the ambient environment.