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ECC RAM should be a human right

dmitrybrant.com

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Re: ECC RAM should be a human right

#141

Post by Retric »

gautamcgoel wrote: post #138
Retric wrote: post #128

Earlier quoted context omitted.

> The company details a 512 GB module of DDR5 memory, running at DDR5-7200, designed for server and enterprise use. That just shows how useful ECC memory is not that these bit flips didn’t occur.

If you scroll down a bit, the article shows a slide from Samsung claiming that DDR5 improves error rates by a factor of 10^6.

That’s a comparison with ODECC vs non ODECC memory chips not DDR5 vs DDR4.

ODECC was added because they wanted to be able to use DDR5 chips which would have had unacceptably large error rates without it. In other words that improvement is before the binning process, so they are selling chips with a vastly higher innate error rate to the point where the average DDR5 stick could actually be worse than the average DDR4 chip, it’s hard to say without large scale testing from multiple manufacturers.

Re: ECC RAM should be a human right

#142

Post by phendrenad2 »

Night_Thastus wrote: post #131
phendrenad2 wrote: post #116

Earlier quoted context omitted.

ECC requires extra circuitry, and that results in more cost, also more testing cost, and also more failed chips (due to more complexity). Most people have very little need for ECC. The author didn't even know that they wanted ECC until they were unlucky enough to get a stick of RAM that failed, and failed in such a way that the OS booted, but a file silently corrupted (not that common, because if a chip fails it usua…

How much more is that cost, and how does it scale? Are we talking 5%, 10%, 30%?

Well, ECC memory is more expensive than non-ECC memory by about 10-20% (according to a quick google search). Part of that may be markup due to people who want ECC being willing to pay for a highly reputable brand sold by a highly-reputable seller (they won't be buying ECC in bulk from amazon marketplace).

Re: ECC RAM should be a human right

#143

Post by bigmadwolf »

hamandcheese wrote: post #75
nimish wrote: post #69

Earlier quoted context omitted.

And AMD, and Nvidia.

AMD ryzen CPUs have ECC support, but it varies by motherboard. My home NAS runs a Ryzen in an ASrock Rack motherboard with ECC ram. I never did figure out a way to verify that the ECC is working/if it is able to report errors (to the kernel?). It was also a bit hard finding the right ram, but there’s a brand called Nemix that I found. I was a bit sketched out by the brand, but the chips themselves were Micron.

To see if ECC is working try overclocking the RAM if possible and looking for EDAC errors (they'll show up in dmesg) or from running edac-util. Eventually you should see something reported.

Re: ECC RAM should be a human right

#144

Post by willis936 »

sliken wrote: post #137
willis936 wrote: post #76

Earlier quoted context omitted.

The GTX 1080 has GDDR5X, which has ECC. I was able to dial in my memory OC on that card by increasing the clock then running memory throughput benchmarks until the throughput was maxed out. At the point where errors start the theroughput would decrease, but nothing would fail. Assuming stationary processes this is pretty nice. Maybe bump back 5% for margin.

I believe that's inside the chip, much like DDR5. However that doesn't help if there's an error introduced by the packages, pin, board traces, CPU pins, or CPU. Better than nothing, but not full ECC either.

You can see here that there are 4 EDC lines used for CRC of every word.

https://web.archive.org/web/20170207162829/https://www.micro...

Re: ECC RAM should be a human right

#145

Post by diarrhea »

wizeman wrote: post #130
diarrhea wrote: post #121

Earlier quoted context omitted.

I was under the impression running such file systems without ECC was kind of reckless and not a solution either? I recall ZFS being “useless” (not technically entirely bulletproof) without ECC.

> I was under the impression running such file systems without ECC was kind of reckless and not a solution either? It's about as reckless as running any other filesystem without ECC [1]. In fact, you're much more likely to discover memory errors earlier if you use a checksumming filesystem than if you use a non-checksumming one. [1] https://news.ycombinator.com/item?id=34477035

Thanks! We already had that discussion, your link is your reply to another comment of mine :^)

I was wrong twice huh!

Re: ECC RAM should be a human right

#146

Post by mike_hock »

sitkack wrote: post #105
mike_hock wrote: post #60

Earlier quoted context omitted.

memtest86 needs to run alone so it can test the entire physical RAM, and the actual, meaningful tests that actually test RAM and not L1 take forever to run. What would you have the OS do?

It still doesn't have full access it doesn't memtest its own code segment for instance. Memtest can also be run as a usermode program (although it needs permission to lock the pages in memory). https://linux.die.net/man/8/memtester

Not the segment where it's currently loaded but it can copy itself around and then test its previous location.
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