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Comment by tyingq | Hacker News Reader

I think the worry is less about crashes and more about silent corruption. Rare, sure, but not that rare:

"Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month"

https://en.wikipedia.org/wiki/Cosmic_ray#Effect_on_electroni...

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More recent, larger-scale studies with modern hardware showed about a 3% chance of a DIMM having an error in a given year: http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf

But these weren't just cosmic-ray-induced errors. The DIMMs with errors were far more likely to have more errors in the future, pointing to faulty memory cells.

Where are you getting the 3 percent chance? Is that per DIMM, per machine? How does that align with these passages?

"About a third of all machines in the fleet experience at least one memory error per year"

"The median number of errors per year for those machines that experience at least one error ranges from 25 to 611."

"Across the entire fleet, 1.3% of machines are affected by uncorrectable errors per year, with some platforms seeing as many as 2-4% affected" is enough to worry me.

Ah, "uncorrected". That leaves "corrected", which only happens for ECC machines, correct?

I prefer more ECC than less, but as a friend of mine noted, most of the data are JPEGs (or video for that matter) and bit flips there usually go unnoticed because they simply adjust the pixel color slightly. So the chance that 1-in-2048-million bits is actually an important metadata bit that corrupts data structures is pretty low.

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