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ECC matters

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Re: ECC matters

#201

Post by numlock86 »

marcosdumay wrote: post #72
defanor wrote: post #66

Earlier quoted context omitted.

I've considered using an AMD CPU instead of Intel's Xeon on the primary desktop computer, but even low-end Ryzen Threadripper CPUs have TDP of 180W, which is a bit higher than I'd like. And though ECC is not disabled in Ryzen CPUs, AFAIK it's not tested in (or advertised for) those, so one won't be able to return/replace a CPU if it doesn't work with ECC memory, AIUI, making it risky. Though I don't know how common i…

Keep in mind that Intel lies about its TDP.

Can you cite something? Sounds interesting.

Re: ECC matters

#202

Post by aborsy »

For the average user, what’s the impact of bit flips in memory in practical terms?

I am not talking about servers dealing with critical data.

Suppose that I maintain a repository (documents, audio and video), one copy in a ZFS-ECC system and one in an ext4-nonECC system.

Would I notice a difference between these two copies after 5-10 years?

That tells us if ECC matters for most people.

Re: ECC matters

#203

Post by 1996 »

miahi wrote: post #53
1996 wrote: post #30

Linus is absolutely right. I am trying to get a laptop with dual NVMe (for ZFS) and ECC RAM. I can't get that, at all - even without the other fancy things I would like such as a 4k OLED with pen/touchscreen. In 2020, even the Dell XPS stopped shipping OLED (goodbye dear 7390!) I will gladly give my money to anyone who sells AMD laptop with ECC. Hopefully, it will show there's demand for "high end yet non bulky lapto…

Lenovo P53 has 3 NVMe slots, 4k OLED with touchscreen (and optional pen) and up to 128GB ECC RAM if you choose the Xeon processor. It's big and heavy, but it exists. I hope AMD will create a better market for the ECC laptop memory (right now it's hard to find + expensive).

I know- I had my eye on this very model, as you can even add a mSata on the WWAN slot to get a 4th drive.

Unfortunately, Lenovo is not selling the P53 anymore, which is exactly why I say I can't get that even in a "bulky" version.

Re: ECC matters

#204

Post by jeffbee »

core-questions wrote: post #164
hosteur wrote: post #144

Earlier quoted context omitted.

How did you track memory errors across thousands of physical machines?

https://github.com/netdata/netdata/issues/1508 Looks like `mcelog --client` might be a starting place? Feed that into your metrics pipeline and alert on it like anything else...

Newer linux have replaced mcelog with edac-util. I think most shops operating systems at that scale are getting their ECC errors out of band with IPMI SEL, though.

Re: ECC matters

#205

Post by theevilsharpie »

cuu508 wrote: post #100
vvanders wrote: post #83

Earlier quoted context omitted.

I don't think Threadripper is a hard requirement for ECC. There's some pretty reasonable TDP processors if you step down from Threadripper.

I haven't seen definite details and test results on these (but haven't looked recently). What specific configurations (CPU, MB, RAM) are known to work? Let's say I have a Ryzen system, how can I check if ECC really works? Like, can I see how many bit flips got corrected in, say, last 24h?

On Windows, to check if ECC is working, run the command 'wmic memphysical get memoryerrorcorrection':

    PC C:\> wmic memphysical get memoryerrorcorrection
    MemoryErrorCorrection
    6
SuperUser has a convenient decoder[1], but modern systems will report "6" here if ECC is working.

When Windows detects a memory error, it will record it in the system event log, under the WHEA source. As a side note, this is also how memory errors within the CPU's caches are reported under Windows.

[1] https://superuser.com/questions/893560/how-do-i-tell-if-my-m...

Re: ECC matters

#206

Post by jgalentine007 »

cbanek wrote: post #152
jackric wrote: post #101

Earlier quoted context omitted.

Do the crash reports include recent solar activity?

Well, I've had to actually worry about radiation bitflips as well. It does happen. But usually not so much on Earth!

One of the tire pressure sensors in my car tires had a bit flip a couple years ago and I had to reprogram it's ID. Luckily it was a subaru, so only a light came on in the dash.

My old Honda crv however would turn traction control on if your pressure was low - which worked by applying brakes to wheels that were slipping. If you were going up a slippery hill you would soon have no power, sliding backwards nearly off the road in nowhere West Virginia on the way to a ski resort.

Re: ECC matters

#207

Post by mark-r »

rahimiali wrote: post #115

I have trouble parsing information from this rant. Is someone willing to translate this into an argument (a string of facts tied by logical steps)?

1. Linux sometimes has crashes, not due to software errors but because of memory glitches. 2. ECC would prevent memory glitches. 3. ECC is hard to find on desktop PCs because Intel uses the feature to differentiate desktop CPUs from server CPUs, so it can charge more for servers. 4. Even when someone like AMD makes the feature available, the market doesn't have ECC DRAM modules or motherboards readily available because Intel killed the demand for it.

Re: ECC matters

#208

Post by throwaway9870 »

aborsy wrote: post #202

For the average user, what’s the impact of bit flips in memory in practical terms? I am not talking about servers dealing with critical data. Suppose that I maintain a repository (documents, audio and video), one copy in a ZFS-ECC system and one in an ext4-nonECC system. Would I notice a difference between these two copies after 5-10 years? That tells us if ECC matters for most people.

This isn't about disk storage, this is about DRAM. A bit flip in DRAM might corrupt data, but could also cause random crashes and system hangs. That generally matters to everyone.

Re: ECC matters

#209

Post by mlyle »

vvanders wrote: post #198
mlyle wrote: post #182

Earlier quoted context omitted.

On AMD, with Ryzen Master, you can set the TDP-envelope of the processor to what you want. Then the boost/frequency/voltage envelope it chooses to operate in under sustained load is different. IMO, shopping by performance/watt makes sense. Shopping by TDP doesn't. (Especially since there is no comparing the AMD and Intel TDP numbers as they're defined differently; neither is the maximum the processor can draw, and In…

TDP matters a fair bit in SFF(Small Form Factor) PCs. For instance the 3700x is a fantastic little CPU since it has a 65W TDP but pretty solid performance. In a sandwich style case you're usually limited to low profile coolers like Noctua L9i/L9a since vertical height is pretty limited.

Performance/watt matters. You can just set TDP to what you want with throttling choices.

If you want a 45W TDP from the 3700X, you can just pop into Ryzen Master and ask for a 45W TDP. Boom, you're running in that envelope.

I think shopping based on TDP is not the best, because it's not comparable between manufacturers and because it's something you can effectively "choose".

Re: ECC matters

#210

Post by jhasse »

dkersten wrote: post #184
incrudible wrote: post #149

Earlier quoted context omitted.

When you say bitflips were "common" on thousands of physical machines, does that mean you observed thousands of bitflips? Otherwise, I would think that an unlikely event becoming 1000x more likely by sheer numbers would have warped your perception. I believe that hardware reliability is mostly irrelevant, because software reliability is already far worse. It doesn't matter whether a bitflip (unlikely) or some bug (li…

Another comment[1] mentioned 1 bitflip per gigabyte per month. If you have a lot of RAM, that's rather a lot. > It doesn't matter whether a bitflip (unlikely) or some bug (likely) causes a node to spuriously fail Except that a bitflip can go undetected. It may crash your software or system, but it also may simply leak errors into your data, which can be far more catastrophic. [1] https://news.ycombinator.com/item?id=…

So can a bug.
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