4 ms·

Dumb question. Why would one want ECC in something that isn't a server? How often do bits in memory actually flip by themselves for it to be warranted?

JoeAltmaier 6y ago
https://stackoverflow.com/questions/4109218/do-gamma-rays-from-the-sun-really-flip-bits-every-once-in-a-while https://stackoverflow.com/questions/4109218/do-gamma-rays-fr... tl;dr: one bit error in 4GB every 72 hours
- coder543 6y ago
  I wish someone with a larger server farm would count the number of reported ECC errors per GB-hour and give us updated numbers. That StackOverflow question is about 10 years old now, and I think it's relying on data even older than that.
  - bentcorner 6y ago
    Someone once did a bit-squatting experiment and "estimates that 614,400 memory errors occur per hour globally". https://nakedsecurity.sophos.com/2011/08/10/bh-2011-bit-squatting-dns-hijacking-without-exploitation/ https://nakedsecurity.sophos.com/2011/08/10/bh-2011-bit-squa... It would be interesting to repeat this experiment today.
  - moonchild 6y ago
    Yes; per the internet archive[1], the data's at least 20 years old. 1. https://web.archive.org/web/20010612184424/http://www.boeing.com/assocproducts/radiationlab/publications/SEU_at_Ground_Level.pdf https://web.archive.org/web/20010612184424/http://www.boeing...
effie 6y ago
Good question. Most people don't really need it, as systems work quite well for long enough time without it and no visible corruption happens. But if you are tech enthusiast who knows a thing or two about errors then you want it, because it makes your system "serious"-grade. It boosts your confidence in quality of your system, and thus self-confidence, ego and bragging rights. Also, it makes your system more professional-grade, where you can monitor ECC errors and, if needed, replace RAM modules or motherboard.
benlivengood 6y ago
https://www.cs.virginia.edu/~gurumurthi/papers/asplos15.pdf https://www.cs.virginia.edu/~gurumurthi/papers/asplos15.pdf is the latest study I can find. Some key findings; error rates per DRAM module and per technology cycle (DDR2, DDR3, and so presumably DDR4) have similar failure rates. Higher altitude has higher failure rates. FIT (failures in time, or failures per billion hours) are about 20-30 per DRAM (18 per DIMM in the study) at a fault level, which may not rise to an error condition. ECC corrects many faults, if present, which don't become errors. So expect a (4GB in this study) DIMM to have a fault once per 200 years on average. Of course, this is server-class hardware running ideal conditions. This is, notably, in stark contrast to Google's results (https://research.google.com/pubs/archive/35162.pdf& https://research.google.com/pubs/archive/35162.pdf&) of about 20,000-70,000 FIT per Mbit, but closer reading suggests that there were a fairly large number of high-fault DIMMs affecting the mean and Google historically bought the cheapest hardware available. Even at this fault rate an average DIMM wouldn't fail in any given month, for example. Personal gaming, browsing and light document work PCs do not need ECC. Video/photo editing/development PCs might be on the threshold for not wanting to produce or store corrupted work. Multiply the risk out for any organization with many people doing the same kind of work where corruption on a single workstation could cause annoying trouble for everyone else.
chithanh 6y ago
According to Google statistics, bit flips are encountered at a rate of 8% per DIMM per year. https://research.google/pubs/pub35162/ https://research.google/pubs/pub35162/ You want ECC in your desktop if you cannot afford your data to become (silently) corrupted. A single bit-flip in a JPEG image can totally ruin it. And you won't notice without opening it, because the thumbnail is unaffected. When you finally notice, the corruption has possibly spread to backups already. For servers that is especially important, because data will reside cached in memory for days or even weeks. Also ECC is often the last line of defense against Rowhammer.

JoeAltmaier 6y ago

https://stackoverflow.com/questions/4109218/do-gamma-rays-from-the-sun-really-flip-bits-every-once-in-a-while https://stackoverflow.com/questions/4109218/do-gamma-rays-fr... tl;dr: one bit error in 4GB every 72 hours

coder543 6y ago
I wish someone with a larger server farm would count the number of reported ECC errors per GB-hour and give us updated numbers. That StackOverflow question is about 10 years old now, and I think it's relying on data even older than that.
- bentcorner 6y ago
  Someone once did a bit-squatting experiment and "estimates that 614,400 memory errors occur per hour globally". https://nakedsecurity.sophos.com/2011/08/10/bh-2011-bit-squatting-dns-hijacking-without-exploitation/ https://nakedsecurity.sophos.com/2011/08/10/bh-2011-bit-squa... It would be interesting to repeat this experiment today.
- moonchild 6y ago
  Yes; per the internet archive[1], the data's at least 20 years old. 1. https://web.archive.org/web/20010612184424/http://www.boeing.com/assocproducts/radiationlab/publications/SEU_at_Ground_Level.pdf https://web.archive.org/web/20010612184424/http://www.boeing...

effie 6y ago

Good question. Most people don't really need it, as systems work quite well for long enough time without it and no visible corruption happens. But if you are tech enthusiast who knows a thing or two about errors then you want it, because it makes your system "serious"-grade. It boosts your confidence in quality of your system, and thus self-confidence, ego and bragging rights. Also, it makes your system more professional-grade, where you can monitor ECC errors and, if needed, replace RAM modules or motherboard.

benlivengood 6y ago

https://www.cs.virginia.edu/~gurumurthi/papers/asplos15.pdf https://www.cs.virginia.edu/~gurumurthi/papers/asplos15.pdf is the latest study I can find. Some key findings; error rates per DRAM module and per technology cycle (DDR2, DDR3, and so presumably DDR4) have similar failure rates. Higher altitude has higher failure rates. FIT (failures in time, or failures per billion hours) are about 20-30 per DRAM (18 per DIMM in the study) at a fault level, which may not rise to an error condition. ECC corrects many faults, if present, which don't become errors. So expect a (4GB in this study) DIMM to have a fault once per 200 years on average. Of course, this is server-class hardware running ideal conditions. This is, notably, in stark contrast to Google's results (https://research.google.com/pubs/archive/35162.pdf& https://research.google.com/pubs/archive/35162.pdf&) of about 20,000-70,000 FIT per Mbit, but closer reading suggests that there were a fairly large number of high-fault DIMMs affecting the mean and Google historically bought the cheapest hardware available. Even at this fault rate an average DIMM wouldn't fail in any given month, for example. Personal gaming, browsing and light document work PCs do not need ECC. Video/photo editing/development PCs might be on the threshold for not wanting to produce or store corrupted work. Multiply the risk out for any organization with many people doing the same kind of work where corruption on a single workstation could cause annoying trouble for everyone else.

chithanh 6y ago

According to Google statistics, bit flips are encountered at a rate of 8% per DIMM per year. https://research.google/pubs/pub35162/ https://research.google/pubs/pub35162/ You want ECC in your desktop if you cannot afford your data to become (silently) corrupted. A single bit-flip in a JPEG image can totally ruin it. And you won't notice without opening it, because the thumbnail is unaffected. When you finally notice, the corruption has possibly spread to backups already. For servers that is especially important, because data will reside cached in memory for days or even weeks. Also ECC is often the last line of defense against Rowhammer.