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0 pointsdeegles5y ago0 comments

Bunch of links to papers here: https://stackoverflow.com/questions/2580933/cosmic-rays-what...

e.g. "2009 Google's paper "DRAM Errors in the Wild: A Large-Scale Field Study" says that there can be up to 25000-75000 one-bit FIT per Mbit (failures in time per billion hours), which is equal to 1 - 5 bit errors per hour for 8GB of RAM after my calculations. Paper says the same: "mean correctable error rates of 2000–6000 per GB per year". "

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lucb1e5y ago

> 1 - 5 bit errors per hour for 8GB of RAM after my calculations

That is way off from what I'm seeing. When launching Factorio I use 90% of my 8GB RAM and never once have I noticed data corruption, and I could tell you how many hours I've played but that would be embarrassing.

The test I did in school with heated-up RAM (the internet said that's when flips should occur more often) also wrote many many gigabytes without a single failure.

Not sure what hardware or temperatures that source is running but it's not DDR3/DDR4 at heats below hairdryer melting temperature because that's where I had to stop the experiment with zero failures.

anfilt5y ago

I would have to find the paper again, but CPU caches can mask the error rate. The cached values also can overwrite any corruption with correct values. This has interesting side effect of protecting commonly accessed data structures and function pointers from causing out right crashing. Same applies to commonly used values in a computation.

Unless you get a bit flip in data structure pointer or function pointer, it just adds an error to computation, but does not just out crash.

Also we are talking only a handful of errors out billions of calculations.

-Edit Also swap space may keep very rarely accessed data from corruption on the other end of spectrum.

Yeroc5y ago

And there are ways to manipulate RAM access patterns to induce errors as described in the initial Rowhammer attack paper plus later RAMBleed papers. Hopefully this newer DDR version is designed to be resistant to this type of attack.

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