Sorry, I wasn’t paying attention and missed that. I apologize.
loads of modern computers don’t use DDR5 or ECC variants of older generations at all, so don’t have any error-correcting memory. If the wrong bit flips, they just crash.
Integrated memory ECC isn’t the only check, it’s an extra redundancy. The point of that paper was to show how often single bit errors occur within one part of a computer system.
memory errors are really rare
Right, because of redundancies. It takes 2 simultaneous bit flips in different regions of the memory in order to cause a memory error and it’s still ~10% chance annually according to the paper I cited.
ECC genuinely is the only check against memory bitflips in a typical system. Obviously, there’s other stuff that gets used in safety-critical or radiation-hardened systems, but those aren’t typical. Most software is written assuming that memory errors never happen, and checksumming is only used when there’s a network transfer or, less commonly, when data’s at rest on a hard drive or SSD for a long time (but most people are still running a filesystem with no redundancy beyond journaling, which is really meant for things like unexpected power loss).
There are things that mitigate the impact of memory errors on devices that can’t detect and correct them, but they’re not redundancies. They don’t keep everything working when a failure happens, instead just isolating a problem to a single process so you don’t lose unsaved work in other applications etc… The main things they’re designed to protect against are software bugs and malicious actors, not memory errors, it just happens to be the case that they work on other things, too.
Also, it looks like some of the confusion is because of a typo in my original comment where I said unrecoverable instead of recoverable. The figures that are around 10% per year are in the CE column, which is the correctable errors, i.e. a single bit that ECC puts right. The figures for unrecoverable/uncorrectable errors are in the UE column, and they’re around 1%. It’s therefore the 10% figure that’s relevant to consumer devices without ECC, with no need to extrapolate how many single bit flips would need to happen to cause 10% of machines to experience double bit flips.
Sorry, I wasn’t paying attention and missed that. I apologize.
Integrated memory ECC isn’t the only check, it’s an extra redundancy. The point of that paper was to show how often single bit errors occur within one part of a computer system.
Right, because of redundancies. It takes 2 simultaneous bit flips in different regions of the memory in order to cause a memory error and it’s still ~10% chance annually according to the paper I cited.
ECC genuinely is the only check against memory bitflips in a typical system. Obviously, there’s other stuff that gets used in safety-critical or radiation-hardened systems, but those aren’t typical. Most software is written assuming that memory errors never happen, and checksumming is only used when there’s a network transfer or, less commonly, when data’s at rest on a hard drive or SSD for a long time (but most people are still running a filesystem with no redundancy beyond journaling, which is really meant for things like unexpected power loss).
There are things that mitigate the impact of memory errors on devices that can’t detect and correct them, but they’re not redundancies. They don’t keep everything working when a failure happens, instead just isolating a problem to a single process so you don’t lose unsaved work in other applications etc… The main things they’re designed to protect against are software bugs and malicious actors, not memory errors, it just happens to be the case that they work on other things, too.
Also, it looks like some of the confusion is because of a typo in my original comment where I said unrecoverable instead of recoverable. The figures that are around 10% per year are in the CE column, which is the correctable errors, i.e. a single bit that ECC puts right. The figures for unrecoverable/uncorrectable errors are in the UE column, and they’re around 1%. It’s therefore the 10% figure that’s relevant to consumer devices without ECC, with no need to extrapolate how many single bit flips would need to happen to cause 10% of machines to experience double bit flips.