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Comment by grndzro | Hacker News Reader

That is why it is important after building/tweaking a system to do stability tests. If it runs full out without errors for 24h then you are fine.

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That's.....not how non-ECC works. Even a little.

RAM bitflips randomly, period. It's just how it works. A cosmic ray can hit the memory chip just right and flip it, there's no way to predict or control that no matter how "stable" your machine is. ECC still does the same, it just has a parity bit on each line to confirm against and flip it back, as needed.

It is how faulty RAM works, and it is sensible to do that.

Not just faulty RAM. As far as I know, all modern RAM is going to have bitflips every once in a while (it even happens with ECC RAM)

I urge you to educate yourself. All RAM works this way, it's the very reason ECC RAM exists and the exact issue it solves.

I have no idea, why you downvoted. Stability test is important step of cluster building. If probability of something broken in new server is 10% then probability of something broken in new cluster of 10 servers is 1-(1-0.1)^10 = 65% .

Because they objection has nothing to do with the original comment. Bitflips are not a RAM stability issue.

Bitflips are not a RAM stability issue, they happen randomly due to radiation, but radiation is not random, especially in my area (I live not far from Chornobyl).

Sure, but you won't solve excessive ambient radiation by running a stress test on your RAM.

A small radioactive («hot») dust particle will not change average radiation level a lot, but may cause problems with memory/cpu. Simple cleaning, by blowing dust out, fixes it. Saw that dozen of times, but years ago.

Did you use a geiger counter to verify the dust was hot? Would something large enough to cause problems with the ram be large enough to detect?

er.. you should probably move. Bitflips aren't the only things radiation does. Bitflips in DNA for example.

Too late, radiation is returned back to almost natural level (about 30% higher than natural). I have detector of radiation, so I can measure it myself. Sometimes wind can bring some radioactive dust from Chornobyl, e.g. after forest fire, but it is much less dangerous.

"Bitflips are not a RAM stability issue."

Cosmic radiation bitflips are BS. No cosmic rays reach ground level. The chance of a, say, Al-28 nucleus successfully penetrating the entire atmosphere is as close to zero as it could be possible to get. Basic physics. Something with such a high charge density won't penetrate ~100km of atmosphere and magnetic field. Even a basic muon wouldn't get through a sheet of aluminum foil and those are still capable of actually getting (barely) through the atmosphere.

The chances of cosmic radiation causing a bitflip are pretty much in the range of "Elvis coming into town on Nessie." Radiation originating from inside the system itself is much more likely a cause.

Attention downvoters: Cosmic rays don't even make it through the atmosphere. They are depleted atomic nuclei which essentially smash into another atom and that's the end of it. Not even multi TeV cosmic rays, which are rare, get through. They never "pass straight through the Earth" either, that's pretty much reserved for neutrinos only. Particles with energies of about 10^18 eV arrive at the rate of about one per square kilometer of atmosphere per century. These very high energy cosmic rays are detected at the ground by looking for the secondary photons, electrons, muons and neutrons that shower large areas of the ground after the primary particle impacts the atmosphere.

Your ground-level bit flips are most likely caused by terrestrial radiation sources, not extra-terrestrial ones. This is just basic physics.

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