Scientists at the Event Horizon Telescope have announced that they’ll use helium-filled hard drives from Western Digital’s HGST division in lieu of conventional hardware. At first glance, this might sound like a marketing stunt — HGST obviously wants high-profile wins for its hermetically-sealed, helium-filled hard drives, and a new research project that combines telescope data from 10 different geographic locations into a single functional observatory might sound like just the ticket. Most of these observatories are built on mountains to take advantage of high-altitude visibility, and it turns out that high altitude observatories run into unique data storage problems.
When the Large Millimeter Telescope began recording data on an array of 32 traditional hard drives, Computerworld reports, 28 of them failed. “We couldn’t use them because the air pressure was so low that the drive heads kept crashing on the hard drive platters,” the project head, Shep Doeleman, told the site. “Using sealed helium drives was the only way to ensure that data could be captured in remote locations, such as our high-altitude observatory in Mexico, where all other storage devices physically failed. Additionally, the high capacity of each drive ensured that we were able to build denser and fewer enclosures overall.”
Safety advisories and other warnings echo Doeleman’s words. Dell doesn’t certify its hard drives to operate above 10,000 feet (at 15,200 feet, the Large Millimeter Telescope is well above this point). The drive heads are designed to float on a cushion of air, but when the air density begins to drop, the pressure within the drive isn’t sufficient to maintain the safety cushion. Multiple articles online discuss the need to hermetically seal any drive that’s going to operate at significant altitude, particularly in military applications. Apparently the researchers had persevered with using 4TB standard drives, despite the high failure rates, but HGST offers an option to increase density to 8TB, cut failure rates dramatically, and cut the cost of assembling the final data set.
Why not use SSDs?
The obvious question would be why the Event Horizon Telescope don’t use SSDs, which wouldn’t suffer altitude problems at all. The most likely answer is because of the sheer amount of data the telescopes collect — each of the telescopes that participates in the project collects over 900TB of data. While the price of consumer SSDs has dropped precipitously in recent years, enterprise SSDs are still quite expensive — and 900TB worth of enterprise solid-state storage is going to make any administrator blanch. HGST’s drives undoubtedly come at a premium, but Doeleman reports that the price/performance curve is still better than the current alternatives.
Once the data is gathered at each individual location, the entire set of drives is physically shipped to the MIT Haystack Observatory, where a network of ~800 CPUs crunches the data through what Doeleman refers to as a “silicon lens.” By using advanced algorithms and specialized processing techniques, scientists are able to analyze the event horizon of the supermassive black hole at the heart of our own galaxy — Sagittarius A*.
The goal of the EHT scientists is to measure and observe the immediate environment around the supermassive black hole to determine its characteristics and nature. It’s fitting that helium, which is relatively abundant in space but relatively scarce on Earth, helps us explore the nature of deep space and the vast structures at the center of our own galaxy.
When the Large Millimeter Telescope began recording data on an array of 32 traditional hard drives, Computerworld reports, 28 of them failed. “We couldn’t use them because the air pressure was so low that the drive heads kept crashing on the hard drive platters,” the project head, Shep Doeleman, told the site. “Using sealed helium drives was the only way to ensure that data could be captured in remote locations, such as our high-altitude observatory in Mexico, where all other storage devices physically failed. Additionally, the high capacity of each drive ensured that we were able to build denser and fewer enclosures overall.”
Safety advisories and other warnings echo Doeleman’s words. Dell doesn’t certify its hard drives to operate above 10,000 feet (at 15,200 feet, the Large Millimeter Telescope is well above this point). The drive heads are designed to float on a cushion of air, but when the air density begins to drop, the pressure within the drive isn’t sufficient to maintain the safety cushion. Multiple articles online discuss the need to hermetically seal any drive that’s going to operate at significant altitude, particularly in military applications. Apparently the researchers had persevered with using 4TB standard drives, despite the high failure rates, but HGST offers an option to increase density to 8TB, cut failure rates dramatically, and cut the cost of assembling the final data set.
Why not use SSDs?
The obvious question would be why the Event Horizon Telescope don’t use SSDs, which wouldn’t suffer altitude problems at all. The most likely answer is because of the sheer amount of data the telescopes collect — each of the telescopes that participates in the project collects over 900TB of data. While the price of consumer SSDs has dropped precipitously in recent years, enterprise SSDs are still quite expensive — and 900TB worth of enterprise solid-state storage is going to make any administrator blanch. HGST’s drives undoubtedly come at a premium, but Doeleman reports that the price/performance curve is still better than the current alternatives.
Once the data is gathered at each individual location, the entire set of drives is physically shipped to the MIT Haystack Observatory, where a network of ~800 CPUs crunches the data through what Doeleman refers to as a “silicon lens.” By using advanced algorithms and specialized processing techniques, scientists are able to analyze the event horizon of the supermassive black hole at the heart of our own galaxy — Sagittarius A*.
The goal of the EHT scientists is to measure and observe the immediate environment around the supermassive black hole to determine its characteristics and nature. It’s fitting that helium, which is relatively abundant in space but relatively scarce on Earth, helps us explore the nature of deep space and the vast structures at the center of our own galaxy.
