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Elevation Plays a Role In Memory Error Rates

Posted by Soulskill on from the another-reason-not-to-calculate-prime-numbers-on-mt.-everest dept.

alphadogg writes "With memory, as with real estate, location matters. A group of researchers from AMD and the Department of Energy's Los Alamos National Laboratory have found that the altitude at which SRAM resides can influence how many random errors the memory produces. In a field study of two high-performance computers, the researchers found that L2 and L3 caches had more transient errors on the supercomputer located at a higher altitude, compared with the one closer to sea level. They attributed the disparity largely to lower air pressure and higher cosmic ray-induced neutron strikes. Strangely, higher elevation even led to more errors within a rack of servers, the researchers found. Their tests showed that memory modules on the top of a server rack had 20 percent more transient errors than those closer to the bottom of the rack. However, it's not clear what causes this smaller-scale effect."

9 of 190 comments (clear)

  1. Heat related? by Anonymous Coward · · Score: 5, Insightful

    Top of the rack tends to get toasty, but is this too simple?

    1. Re:Heat related? by spike+hay · · Score: 4, Interesting

      Radiation blockage is mostly a function of mass the rays have to go through. The vast majority of cosmic rays are blocked by the 14 pounds per square inch/100 kilopascals of air above us. That means that a square inch of ground at sea level has 14 pounds of air above it. A square inch section of a rack above you would probably be in the pounds as well, and would block a good portion.

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    2. Re:Heat related? by DeathToBill · · Score: 4, Interesting

      I was looking into RAM error rates a week or so ago. There's not a lot of research around, but I recall seeing suggestions that error rates were significantly smaller if the chips were mounted vertically rather than horizontally - because vertically mounted chips present a lower vertical cross-section and most error-inducing cosmic rays come at near-vertical inclination.

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  2. basements by Anonymous Coward · · Score: 5, Funny

    Another reason for nerds to stay in the basement

  3. This isn't news by dszd0g · · Score: 4, Informative

    This isn't news. Companies that make supercomputers have known this for decades. The one I worked for 15 years ago used a high elevation test environment in Colorado to verify error correcting capabilities. Even the article says that the results were not a surprise.

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    1. Re:This isn't news by edibobb · · Score: 4, Informative

      From the article: "It is well known that the altitude at which a data center resides has consequences with regards to machine fault rates. The two primary causes of increased fault rates at higher altitude are reduced cooling due to lower air pressure and increased cosmic ray-induced neutron strikes."

  4. This is news? by Nkwe · · Score: 4, Funny

    If you get high you can lose your memory?

  5. Re:That's interesting! by Antipater · · Score: 5, Funny

    Another interesting idea would be to do the same experiment by latitude. Does the Arctic Region Supercomputing Center have a higher rate than the Maui Supercomputing Center?

    They tried to do that test a few years back, but both research teams mysteriously disappeared. The leading hypothesis is that the Arctic team was eaten by polar bears, but nobody has any idea what happened to the Maui team. The only clue left at the scene was a nearly-empty glass of pina colada.

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  6. Muons by Roger+W+Moore · · Score: 4, Informative

    Then wouldn't you expect a cascading rate of failures from 20% down to the baseline bottom rack in a linear fashion?

    The majority of cosmic rays that make it this far are muons. These are relatively penetrating and I highly doubt that a few centimetres of metal and plastic will have anything like a 20% effect. 60m underground with the ATLAS detector at the LHC we still get a reasonable rate of cosmic rays and we use them for calibration when there is no beam. While the rate is reduced 60m of rock is far, far more shielding than a few computers plus many cosmics passing through you come at an angle so the stack above will have no effect on shielding these.

    I expect that heat and vibration will be the most likely causes.