4 ms·

Non-ECC RAM bit flips are pretty common at modern densities. They can cause everything from a stray pixel on screen, to crashes, to corrupted files and file sys

Non-ECC RAM bit flips are pretty common at modern densities. They can cause everything from a stray pixel on screen, to crashes, to corrupted files and file systems. At $dayjob we only have like 200 laptops but our help desk staff find 1-3 bad non-ECC DIMMs a year causing crashes or borked files.

me_me_me 7y ago
Well, you said it... 3 crashes a year vs cost of 200 ECC RAM. (say refresh of pc every 3 years). So in lifetime of those machines you will experience 9 crashes. Is it really cost effective? Also file versioning, automatic backups of files should be a standard in any serious business. So in reality no work would be lost to crash, only bit of time.
- zaarn 7y ago
  The problem is that backups don't work if the file is already corrupted when it's being written, most filesystems aren't very robust to on-disk corruption (and even those that are like ZFS have quite a few fun bugs if there is memory corruption present). Even versioning will not save you if you version already corrupted data.
  - me_me_me 7y ago
    I am programing over 10 years, that never happened to me and I never heard of anyone who had experienced something like that. Your words/excels save a copy of files upon opening (to handle crashes or corruption). Is it worth entertaining this scenario? Unless you are running on a space probe or nuclear facility pc that's non-issue worth any time.
    - zaarn 7y ago
      Oh, I've experienced such things, it's a matter of scale. If you have 1000 machines running, the probability of one eating importing project data due to cosmic bitflips starts to matter.
    - tatersolid 7y ago
      Processors use ECC in their on-board caches for a reason. Transient memory errors are not uncommon when you have many terabytes of collective RAM in use. Google’s study reports 8% of DIMMS see a transient error per year. https://ai.google/research/pubs/pub35162 https://ai.google/research/pubs/pub35162
gnode 7y ago
> find 1-3 bad non-ECC DIMMs The problem of faulty memory is separate and can be addressed by memory testing (which can even be run while computers are online). My understanding is that ECC's main purpose is to guard against corruption of non-faulty memory, due to ionising radiation for instance. It's rare for this to be a problem in normal scenarios (not in space or high-altitude), and use cases.

me_me_me 7y ago

Well, you said it... 3 crashes a year vs cost of 200 ECC RAM. (say refresh of pc every 3 years). So in lifetime of those machines you will experience 9 crashes. Is it really cost effective? Also file versioning, automatic backups of files should be a standard in any serious business. So in reality no work would be lost to crash, only bit of time.

zaarn 7y ago
The problem is that backups don't work if the file is already corrupted when it's being written, most filesystems aren't very robust to on-disk corruption (and even those that are like ZFS have quite a few fun bugs if there is memory corruption present). Even versioning will not save you if you version already corrupted data.
- me_me_me 7y ago
  I am programing over 10 years, that never happened to me and I never heard of anyone who had experienced something like that. Your words/excels save a copy of files upon opening (to handle crashes or corruption). Is it worth entertaining this scenario? Unless you are running on a space probe or nuclear facility pc that's non-issue worth any time.
  - zaarn 7y ago
    Oh, I've experienced such things, it's a matter of scale. If you have 1000 machines running, the probability of one eating importing project data due to cosmic bitflips starts to matter.
  - tatersolid 7y ago
    Processors use ECC in their on-board caches for a reason. Transient memory errors are not uncommon when you have many terabytes of collective RAM in use. Google’s study reports 8% of DIMMS see a transient error per year. https://ai.google/research/pubs/pub35162 https://ai.google/research/pubs/pub35162

gnode 7y ago

> find 1-3 bad non-ECC DIMMs The problem of faulty memory is separate and can be addressed by memory testing (which can even be run while computers are online). My understanding is that ECC's main purpose is to guard against corruption of non-faulty memory, due to ionising radiation for instance. It's rare for this to be a problem in normal scenarios (not in space or high-altitude), and use cases.