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ECC matters

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Re: ECC matters

#31

Post by reader_mode »

IgorPartola wrote: post #18
eloy wrote: post #5

Earlier quoted context omitted.

He does explain it: > We have decades of odd random kernel oopses that could never be explained and were likely due to bad memory. And if it causes a kernel oops, I can guarantee that there are several orders of magnitude more cases where it just caused a bit-flip that just never ended up being so critical. It might be false, but I think it's a reasonable assumption.

To someone on HN who isn’t familiar with what ECC does that explains nothing about how ECC works and how it could have prevented these situations. Or how often they really happen.

It takes 5 seconds to Google ECC memory if you're really interested and if you're working on kernel related stuff you 99.9999% know what it is.

Re: ECC matters

#32

Post by simias »

raverbashing wrote: post #23
simias wrote: post #13

Earlier quoted context omitted.

For a 2nd language speaker making these homophonic mistakes is actually a sign of fluency. It means that you just transcribe a mental flow of words instead of consciously constructing the language. The first time I wrote "your" instead of "you're" in English I thought it was quite a milestone!

> For a 2nd language speaker making these homophonic mistakes is actually a sign of fluency. I kinda disagree because while the homophony works in (spoken) English in written it stands as a sore thumb. So yeah you will make it if you only heard it but doesn't know the written form. (And in their native language it's probably two unrelated words, so that might intensify the feeling of wrongness)

I mean, my native language is French where "your" is "ton" and "you're" is "tu es", yet it (rarely) happens that I mix them up in English. If I proofread I'll spot it almost every single time, but if I'm just typing my "stream of consciousness" my brain's speech-to-text module sometimes messes up.

Re: ECC matters

#33

Post by loeg »

dijit wrote: post #16

I beg this, every time this conversation comes up it’s the same answer “I don’t see a problem”. It’s so easy to chalk these kind of errors to other issues, a little corruption here, a running program goes bezerk there- could be a buggy program or a little accidental memory overwrite. Reboot will fix it. But I ran many thousands of physical machines, petabytes of RAM, I tracked memory flip errors and they were _common…

Yeah, it's real obnoxious of Intel to silo ECC support off into the Xeon line, isn't it? I switched to ECC memory in 2013 or 2014 with a Xeon E3 (fundamentally a Core i7 without the ECC support fused off) and of course a Xeon-supporting motherboard (with weird "server board" quirks: e.g., no on-board sound device).

I love that AMD doesn't intentionally break ECC on its consumer desktop platforms and upgraded to the Threadripper in 2017.

Re: ECC matters

#34

Post by bitcharmer »

freeqaz wrote: post #10

I bought ECC RAM for my laptop and it definitely was about 4x the price. It's valuable to me for a few reasons -- peace of mind being a big one. Bit flips happen and are real. I really wish ECC was plentiful and not brutally expensive!

This is the first time I hear about a laptop that supports ECC memory. Could you please share the make and model?

Re: ECC matters

#35

Post by loeg »

ekianjo wrote: post #29
simias wrote: post #9

I used to be pretty skeptical of ECC for consumer-grade hardware, mainly because I felt that I'd always prefer cheaper/more RAM over ECC RAM even if it meant that I'd get a couple of crash every year due to rogue bitflips. For servers it's a different story, but for a desktop I'm fine dealing with some instability for better performance. But these days with the RAM density being so high and bitflipping attacks being…

> no good reason not to switch to ECC everywhere. Not all CPUs support ECC however.

(Intel)

Re: ECC matters

#36

Post by tomxor »

bitcharmer wrote: post #28
phh wrote: post #20

I don't know if ECC is that important, but reliability of RAM (or any storage) feels pretty crazy to me. 128GB being refreshed every second for a month error requires that the per-bit refresh process has a reliability of 99.9999999999999999% to be flawless. Considering we are dealing with quantum effects (which are inherently probabilistic), I wouldn't trust myself to design anything like that. Now back to ECC, I'll…

A system on Earth, at sea level, with 4 GB of RAM has a 96% percent chance of having a bit error in three days without ECC RAM. With ECC RAM, that goes down to 1.67e-10 or about one chance in six billions. So I'd say ECC is not only important but insanely impactful. There's a reason why many organizations don't even want to hear about getting rigs with non-ECC memory.

I like when people back up their claims with numbers, but would you mind describing roughly what that 96% probability of error is based upon?

I understand altitude has some kind of proportionality to cosmic ray exposure, and number of bits will multiply the probability of an error.. I'm presuming there is also an inherent error rate to DRAM separate from environment. But what are those numbers.

Re: ECC matters

#37

Post by leetcrew »

raverbashing wrote: post #23
simias wrote: post #13

Earlier quoted context omitted.

For a 2nd language speaker making these homophonic mistakes is actually a sign of fluency. It means that you just transcribe a mental flow of words instead of consciously constructing the language. The first time I wrote "your" instead of "you're" in English I thought it was quite a milestone!

> For a 2nd language speaker making these homophonic mistakes is actually a sign of fluency. I kinda disagree because while the homophony works in (spoken) English in written it stands as a sore thumb. So yeah you will make it if you only heard it but doesn't know the written form. (And in their native language it's probably two unrelated words, so that might intensify the feeling of wrongness)

meh, plenty of (intelligent!) native english speakers do not know all the canonical grammar rules. english contains a lot of what could be considered error correction bits, so it doesn't usually impede understanding. syntactically perfect english with weird/misused idioms (common among non-native speakers with lots of formal education) is harder to understand in my experience. I imagine this is true of most natural languages.

Re: ECC matters

#38

Post by rhn_mk1 »

loeg wrote: post #33
dijit wrote: post #16

I beg this, every time this conversation comes up it’s the same answer “I don’t see a problem”. It’s so easy to chalk these kind of errors to other issues, a little corruption here, a running program goes bezerk there- could be a buggy program or a little accidental memory overwrite. Reboot will fix it. But I ran many thousands of physical machines, petabytes of RAM, I tracked memory flip errors and they were _common…

Yeah, it's real obnoxious of Intel to silo ECC support off into the Xeon line, isn't it? I switched to ECC memory in 2013 or 2014 with a Xeon E3 (fundamentally a Core i7 without the ECC support fused off) and of course a Xeon-supporting motherboard (with weird "server board" quirks: e.g., no on-board sound device). I love that AMD doesn't intentionally break ECC on its consumer desktop platforms and upgraded to the T…

Doesn't intel make ECC available on the i3 line of CPUs?

Re: ECC matters

#39

Post by turminal »

IgorPartola wrote: post #3

I wish this was more of a cohesive argument. He says he thinks it’s important and points to row-hammer problems but doesn’t explain why. Probably because the audience it was written for already knows the arguments of why, but this is not the best argument. If in doubt, get ECC. Do your own research on how it works and why. This post won’t explain it, just will blame Intel (probably rightfully so).

It's a message in a thread from a technological forum. I think its intended audience are people already familiar with ECC unlike here on HN.

Re: ECC matters

#40

Post by nix23 »

I always have that conversation when ZFS comes up. Some peoples think ZFS NEEDS ECC, but in fact ZFS needs ECC much as every single one FS in Linux. And every single reliable Machine needs ECC.
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