4 ms·

I don't know about anyone else, but when I'm seeking advice about software from people on the internet whom I don't know personally, I tend to weight the words

by __jal 10y ago

I don't know about anyone else, but when I'm seeking advice about software from people on the internet whom I don't know personally, I tend to weight the words of the authors of the software in question more highly than that of people who didn't write it. There are probably exceptions to that I'm currently forgetting. And the authors of ZFS, from the Sun days on, have been consistently and repeatedly saying that if you care about your data, use ECC. I personally don't get why people seem so resistant to using ECC. It isn't that much more expensive and we know these errors happen in around 8% of DIMMS[1]. It reminds me of people I know who refuse to buy a decent power supply and then complain about hardware failures because of shoddy power. Personally, paying a slight premium to avoid an almost one in 10 likelihood of silent data corruption seems like a no-brainer to me. But then, I care about my data. Edit: to be clear, ZFS will perform less dangerously with non-ECC ram than a filesystem that doesn't checksum with non-ECC, because it will detect Bad Things happening and tell you about it. ECC helps avoid the problems in the first place. [1] http://research.google.com/pubs/pub35162.html http://research.google.com/pubs/pub35162.html

wtallis 10y ago
ECC isn't that much more expensive, if you already have a processor and motherboard that give you that option. If you're trying to use ZFS on surplus consumer Intel equipment, ECC is a major expense. And aside from the cost issue, I don't think people are resistant to using ECC. You have probably just misinterpreted people who are justifiably shooting down ZFS/ECC scaremongering: Advising people to never use ZFS without ECC RAM is bad advice, because the advice should simply be to use ECC RAM if you want enterprise grade reliability, whether or not ZFS is part of the picture. Some people aren't in need of that level of reliability but can still benefit from ZFS, and they shouldn't be misled into thinking that ZFS has some particular need for ECC RAM.
- __jal 10y ago
  I agree on the last part, and I think the particular weirdness here is a result of ZFS historically mentioning the value of ECC a lot more than other FSes. I think this probably makes people think that ZFS in some way depends on it more than others, rather than simply pointing out that there's a disturbingly high chance of encountering a problem without it that applies to everything. And sure, if you're building a frankenbox, ECC is probably not an option, or the sort of expense that takes it out of the frankenbox category. I do hope that folks wouldn't store important data on dodgy hardware, but that is about more than RAM, and also none of my business. I don't believe I'm misinterpreting people's reactions - I've witnessed people assert that ECC is a scam, waste of money and similar. Even after I point them to that link I posted above, they still seem to believe that It Won't Happen To Them. ("I don't have millions of machines.") In any case, I still find it frankly bizarre that people run the risk with important data. If you asked people if they wanted to buy a CPU that had an ~8% chance of undetectably lying to them, I'm pretty sure the vast majority would at least want to spring for the premium one that allows at the least detecting the lie.
  - wtallis 10y ago
    > I've witnessed people assert that ECC is a scam, waste of money and similar. Even after I point them to that link I posted above, they still seem to believe that It Won't Happen To Them. ("I don't have millions of machines.") If by your own citation 92% of DIMMs operate with zero errors per year, and a consumer machine has at most four DIMMs, then it is actually pretty likely that any given consumer machine will operate without RAM errors even without ECC. And when you multiply by the low probability that a DRAM error will cause catastrophic data loss, then it is very easy to come to a reasonable conclusion that ECC is not worth the expense.
    - __jal 10y ago
      Hey, it is your data. I personally don't like gambling with mine, but yours is none of my business. Again, I don't know how many people out there buy other products with a nearly 1 in 10 chance of undetectably not performing the function they are supposed to perform, but it seems nutty to me. Although that line of thought does go some way towards explaining the vitamin business...
      - wtallis 10y ago
        It's disingenuous of you to keep putting the error probabilities in terms like "nearly 1 in 10" without acknowledging the context that you're talking about the probability of a transient error occurring at any time over the course of a full year of continuous operation. Most people actually are comfortable with the idea that their equipment will have occasional downtime or faults, but you're trying to paint a very different picture.
        __jal 10y ago
        Buddy, I would heartily encourage you to believe whatever you makes you happy. Your insult is false and petty, and I think you're pretty wrong about the rest of that. I personally consider it pretty disingenuous to call a fault that damages data on disk 'transient'. The root cause may have been transient, but the damage doesn't go away if/when a stuck bit functions normally again. Or do you consider a stroke leading to paralysis a transient injury? I'd also like to see a cite that "most people actually are comfortable with the idea that..." a 'transient' fault that scrambles random data they've chosen to keep. Where, exactly, are you getting this? Finally, assuming you have some actual basis for that claim, how many of those people run ZFS? You wouldn't conflate nontechnical people who buy the cheapest box at Best Buy with folks who take the time to configure software RAID across several disks using a nonstandard filesystem, would you?
mikeash 10y ago
"if you care about your data, use ECC." This is great advice, but it has nothing to do with ZFS. It's true no matter what filesystem you use.
- agumonkey 10y ago
  It's a good sense thing. Probably means "Don't take steps to use ZFS for data integrity if you don't use simpler, lower level precautions".

by __jal 10y ago

wtallis 10y ago

ECC isn't that much more expensive, if you already have a processor and motherboard that give you that option. If you're trying to use ZFS on surplus consumer Intel equipment, ECC is a major expense. And aside from the cost issue, I don't think people are resistant to using ECC. You have probably just misinterpreted people who are justifiably shooting down ZFS/ECC scaremongering: Advising people to never use ZFS without ECC RAM is bad advice, because the advice should simply be to use ECC RAM if you want enterprise grade reliability, whether or not ZFS is part of the picture. Some people aren't in need of that level of reliability but can still benefit from ZFS, and they shouldn't be misled into thinking that ZFS has some particular need for ECC RAM.

__jal 10y ago
I agree on the last part, and I think the particular weirdness here is a result of ZFS historically mentioning the value of ECC a lot more than other FSes. I think this probably makes people think that ZFS in some way depends on it more than others, rather than simply pointing out that there's a disturbingly high chance of encountering a problem without it that applies to everything. And sure, if you're building a frankenbox, ECC is probably not an option, or the sort of expense that takes it out of the frankenbox category. I do hope that folks wouldn't store important data on dodgy hardware, but that is about more than RAM, and also none of my business. I don't believe I'm misinterpreting people's reactions - I've witnessed people assert that ECC is a scam, waste of money and similar. Even after I point them to that link I posted above, they still seem to believe that It Won't Happen To Them. ("I don't have millions of machines.") In any case, I still find it frankly bizarre that people run the risk with important data. If you asked people if they wanted to buy a CPU that had an ~8% chance of undetectably lying to them, I'm pretty sure the vast majority would at least want to spring for the premium one that allows at the least detecting the lie.
- wtallis 10y ago
  > I've witnessed people assert that ECC is a scam, waste of money and similar. Even after I point them to that link I posted above, they still seem to believe that It Won't Happen To Them. ("I don't have millions of machines.") If by your own citation 92% of DIMMs operate with zero errors per year, and a consumer machine has at most four DIMMs, then it is actually pretty likely that any given consumer machine will operate without RAM errors even without ECC. And when you multiply by the low probability that a DRAM error will cause catastrophic data loss, then it is very easy to come to a reasonable conclusion that ECC is not worth the expense.
  - __jal 10y ago
    Hey, it is your data. I personally don't like gambling with mine, but yours is none of my business. Again, I don't know how many people out there buy other products with a nearly 1 in 10 chance of undetectably not performing the function they are supposed to perform, but it seems nutty to me. Although that line of thought does go some way towards explaining the vitamin business...
    - wtallis 10y ago
      It's disingenuous of you to keep putting the error probabilities in terms like "nearly 1 in 10" without acknowledging the context that you're talking about the probability of a transient error occurring at any time over the course of a full year of continuous operation. Most people actually are comfortable with the idea that their equipment will have occasional downtime or faults, but you're trying to paint a very different picture.
      - __jal 10y ago
        Buddy, I would heartily encourage you to believe whatever you makes you happy. Your insult is false and petty, and I think you're pretty wrong about the rest of that. I personally consider it pretty disingenuous to call a fault that damages data on disk 'transient'. The root cause may have been transient, but the damage doesn't go away if/when a stuck bit functions normally again. Or do you consider a stroke leading to paralysis a transient injury? I'd also like to see a cite that "most people actually are comfortable with the idea that..." a 'transient' fault that scrambles random data they've chosen to keep. Where, exactly, are you getting this? Finally, assuming you have some actual basis for that claim, how many of those people run ZFS? You wouldn't conflate nontechnical people who buy the cheapest box at Best Buy with folks who take the time to configure software RAID across several disks using a nonstandard filesystem, would you?

mikeash 10y ago

"if you care about your data, use ECC." This is great advice, but it has nothing to do with ZFS. It's true no matter what filesystem you use.

agumonkey 10y ago
It's a good sense thing. Probably means "Don't take steps to use ZFS for data integrity if you don't use simpler, lower level precautions".