▷ Hard drives made of helium: all the information?

In November 2013, HGST, a subsidiary of Western Digital, introduced the world to the first helium-filled hard drive available on the market. The 6TB drive was not only unique in being filled with helium instead of air, but it was the largest capacity hard drive available. A little over 4 years later helium-filled 14TB drives are available, and drives up to 25TB helium-filled will soon arrive. Everything about hard drives made of Helium.

Index of contents

Helium on a hard drive and what are the difficulties

Inside an air-filled hard drive, there are disk drives that spin rapidly and spin at a certain speed, for example at 7200 rpm. The air inside adds a considerable amount of drag on the plates which in turn requires an appreciable amount of additional energy to rotate the plates. Replacing the air inside a hard drive with helium reduces the amount of resistance, thus reducing the amount of energy required to spin the platters, usually by 20%.

One problem with helium is that it is lighter than air, so it tends to leak out of the device. This was one of the key challenges in using helium inside a hard drive: Helium escapes from most containers, even if they are well sealed. It took years for hard drive manufacturers to create containers that could hold helium while still functioning as a hard drive. This container innovation allows helium-filled units to operate to manufacturer-given specifications throughout their useful lives.

The read / write heads inside a hard disk actually fly over the surface of the disk in what we call a "gas bearing". Without gas, the heads will collide with the disc. The problem with air is that it creates turbulence, so the engineers looked for a less dense element. Hydrogen is the least dense element, but it is too flammable so it is not a good idea to use it in a device that produces heat. Helium is the second lightest and second most abundant element in the observable universe, and since helium is a noble gas, it does not react with anything. Being 1/7 of the density of air, replacing air with helium reduces turbulence inside the drive, providing a host of benefits.

Advantages of hard drives made of helium

Helium has several advantages that provide great benefits to end users:

• Zoom tracks together: tracks closer together means more data tracks per disk = more data per HDD. Thinner discs = more discs (5 discs are now 8 discs) = more data per HDD. Thinner discs require less power to spin. Helium creates less drag resistance and requires less power to spin discs. Less drag = less noise.

Reliability hard drives with helium vs air

It is already clear that the use of helium in hard disks provides many advantages compared to the use of air, the next point to analyze is reliability, since it can be thought that helium hard disks will be less reliable due to the ease with which this noble gas tends to leak to the outside. Backblaze is usually the best analyst when it comes to seeing the reliability of hard drives, so we are going to rely on their data.

The most obvious observation is that there appears to be little difference in the annualized failure rate (AFR) based on whether they contain helium or air. The prediction is that helium units will eventually prove to have a lower AFR. However, Backblaze data shows that helium-filled hard drives fail only 1.03% on average, while air-filled hard drives fail 1.06%. One conclusion, given this evidence, is that helium does not affect the AFR of hard drives compared to air-filled drives

Mean of HDD failures studied
Air	1.06%
Helium	1.03%

The hypothesis is that after normalizing the data so that the helium and air filled units have the same use, the helium filled units we use will continue to have a lower annualized failure rate compared to the air units. This trend is expected to continue for at least the next year. Also keep in mind that the technology of helium hard drives is newer, so the room for improvement is larger than in air-based ones.

We recommend reading our article on The best hard drives on the market

As a final conclusion we can say that helium-based hard drives have many advantages over air-based ones, and a priori they do not suffer from a lower useful life, which is the main drawback that can be thought to have. Therefore, it is clear that the future of hard drives stops with the use of helium, a noble gas that opens the doors to ever greater capacities with less energy use.

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