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Great! Question: When 64K DRAM first appeared, I remember a cover article in EDN(?) claiming that nothing denser could ever be built, because cosmic radiation w
by drfuchs 6y ago
Great! Question: When 64K DRAM first appeared, I remember a cover article in EDN(?) claiming that nothing denser could ever be built, because cosmic radiation would zap individual electrons, and thus flip bits too frequently, and there was nothing you could do to protect from it. So, how was that thinking wrong?
- kens 6y agoThey discovered that most of the DRAM soft errors were due to alpha particles from the ceramic packaging. Changing the packaging solved most of the problem. There are still bit flips due to cosmic rays but the rate is low enough that most people don't care. ECC memory can be used if errors are a problem. More details on Wikipedia: https://en.wikipedia.org/wiki/Soft_error#Alpha_particles_from_package_decay https://en.wikipedia.org/wiki/Soft_error#Alpha_particles_fro...
- formerly_proven 6y agoSome of Sun's servers famously suffered big reliability problems due to using IBM SRAM as caches, which is said to have had elevated error rates due to more alpha-emitting contaminants in their particular package filler.
- kens 6y agoI was at Sun at the time (although not working on that), and these memory errors were a catastrophic problem for Sun. Customers were paying a lot of money for Sun's reliability and then systems started mysteriously having problems and Sun couldn't figure out why.
- lokedhs 6y agoI was there too. That would be the ecache problem, right? I was in the service division at the time, and yes, it was a serious issue. However, if I recall correctly it was limited to the E10K. It was the flagship machine, so of course it got all the attention, but most customers didn't suffer from it.
- askvictor 6y agoAt least they weren't due to radioactive cows: https://www.jakepoz.com/debugging-behind-the-iron-curtain/ https://www.jakepoz.com/debugging-behind-the-iron-curtain/