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Should I buy ECC memory? (2015)

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Re: Should I buy ECC memory? (2015)

#171

Post by duskwuff »

codinghorror wrote: post #163
spullara wrote: post #57

I reproduced this by bit-squatting cloudfront.net after reading about it. So many memory errors! http://dinaburg.org/bitsquatting.html Loved the variety as well. Sometimes though requests came to me the Host header was correct!

Wait so when someone typoes cnn.com as con.com, that is ipso facto a memory error? I guess I could see that if the characters are radically far apart on the keyboard? But doesn't a simpler explanation like "one person out of billions with Internet access typed the wrong thing" seem a lot more likely?

Domains that are only used as CDNs, like cloudfront.com, are almost never typed into an address bar. Errors in the domain name are more frequently the result of a bit-flip error.

Re: Should I buy ECC memory? (2015)

#172

Post by ori_b »

blackflame7000 wrote: post #112
mjevans wrote: post #20

A better question is why /shouldn't/ you use ECC memory? Generally the answer to this is any context where you legitimately do NOT care about your data at all, but you still care about costs. This predominately devolves in to consumption only gaming systems. In all other cases everyone would be better served (in the long run) by buying ECC RAM.

a common network topology is to have a load balancer distribute load to a number of cheap Http servers which internally connect to a centralized and powerful database server. In this case only the database server really needs ECC ram. The system is designed to be fault tolerant for any individual HTTP server node so the increased cost vs the problem it solves doesn't make sense. I guess you could argue that a random…

> In this case only the database server really needs ECC ram.

That's only true if the database is read only. Otherwise, you will still insert corrupt data into it.

Re: Should I buy ECC memory? (2015)

#173

Post by dagw »

yuhong wrote: post #154
rfrank wrote: post #135

Earlier quoted context omitted.

Was that the case before Ryzen? I know their new CPUs support ECC, but I'm not sure for earlier generations.

I think it was common for AM3 for example too.

It was technically supported by the hardware, but not by many motherboard and BIOS's.

Re: Should I buy ECC memory? (2015)

#174

Post by rasz »

tdb7893 wrote: post #114
sitkack wrote: post #109

Earlier quoted context omitted.

I have hit soft errors in every desktop machine that used ECC. Either I have bad luck, ECC causes the errors or third thing. I think ECC should be mandated for anything except toys and video players.

How much more expensive is ECC ram? I don't have it and I've never experienced obvious issues, if it's a lot more expensive it's not really worth it for the once or twice the desktop will likely experience an actual issue

usually its cheaper because of server market forced upgrade cycle surplus. Problem is its mostly Buffered/Registered ECC which cant be used in desktop motherboards.

Re: Should I buy ECC memory? (2015)

#175

Post by alkonaut »

For servers this is more or less a no brainer: it's not a huge extra cost and a failure will cost you more than the extra cost.

For a regular desktop system for personal use it's not so easy. The data volumes are much smaller, the temperature environments are usually better, they aren't running (other than maybe idling) 24/7, most of the stuff that is in ram isn't going to be mission critical (i.e. you don't have 32Gb of RAM filled with customer database records, you have it filled with read only FPS textures, compiler caches etc).

Unlike a business that has tons of data that is mutated, my data is mostly immutable such as photos etc. It's not a continuously changing dataset where a bit flip in memory is likely to find its way into my data and then into my backups which would be the case e.g. for databases or big creative work (movie editing etc).

Re: Should I buy ECC memory? (2015)

#176

Post by raarts »

Taek wrote: post #46
muro wrote: post #34

Earlier quoted context omitted.

I don't understand why anyone would run their own email server. Cloud offerings work so well and are cheap.

If you are using the cloud for email they can usually see all of your activity. Email is also how you typically reset passwords. It can expose corporate secrets. In practice, nobody encrypts their email. And even if they do, the cloud still gets all the metadata. Running your own trades the above issues for other issues, but depending on your priorities and fears it might be worth doing.

> in practice nobody encrypts their email.

I work in the defence industry. All attachments must be encrypted. Also, all customer data must be stored in the same country.

Re: Should I buy ECC memory? (2015)

#177

Post by lomnakkus »

fgonzag wrote: post #139
gh02t wrote: post #124

Earlier quoted context omitted.

It's significantly more expensive, usually around 30-100% more, depending on capacity. IMO not worth it on a desktop, possibly worth it on a home server or a serious workstation. Plus your CPU and motherboard has to support it, which is a pain with Intel's consumer lineup.

Good thing ryzen supports ECC OBO. Just waiting on motherboard support for it.

I think I may go AMD (again) for this very reason.

(Generally, I don't think ECC actually does matter that much for us casual/home users, but I like to reward the people who actually do make it easy to "do the right thing". Same deal as only purchasing AMD graphics cards since 2005-ish(?).)

Re: Should I buy ECC memory? (2015)

#178

Post by Tomte »

Rehashing an old comment:

IEC 61508 documents an estimate of 700 to 1200 fit/MBit (fit = "failure in time"; per 10e-9 hours of operation) and gives the following sources:

a) Altitude SEE Test European Platform (ASTEP) and First Results in CMOS 130 nm SRAM. J-L. Autran, P. Roche, C. Sudre et al. Nuclear Science, IEEE Transactions on Volume 54, Issue 4, Aug. 2007 Page(s):1002 - 1009

b) Radiation-Induced Soft Errors in Advanced Semiconductor Technologies, Robert C. Baumann, Fellow, IEEE, IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 5, NO. 3, SEPTEMBER 2005

c) Soft errors' impact on system reliability, Ritesh Mastipuram and Edwin C Wee, Cypress Semiconductor, 2004

d) Trends And Challenges In VLSI Circuit Reliability, C. Costantinescu, Intel, 2003, IEEE Computer Society

e) Basic mechanisms and modeling of single-event upset in digital microelectronics, P. E. Dodd and L. W. Massengill, IEEE Trans. Nucl. Sci., vol. 50, no. 3, pp. 583–602, Jun. 2003.

f) Destructive single-event effects in semiconductor devices and ICs, F. W. Sexton, IEEE Trans. Nucl. Sci., vol. 50, no. 3, pp. 603–621, Jun. 2003.

g) Coming Challenges in Microarchitecture and Architecture, Ronen, Mendelson, Proceedings of the IEEE, Volume 89, Issue 3, Mar 2001 Page(s):325 – 340

h) Scaling and Technology Issues for Soft Error Rates, A Johnston, 4th Annual Research Conference on Reliability Stanford University, October 2000

i) International Technology Roadmap for Semiconductors (ITRS), several papers.

If that's correct, the math is simple: you have bit flips in your PC about once a day.

It's just that (a) you often won't notice those transient errors (one pixel in your multi-megapixel photo is one bit off) and (b) a lot of your RAM is probably unused.

Re: Should I buy ECC memory? (2015)

#179

Post by Tuna-Fish »

indolering wrote: post #142
sytelus wrote: post #55

Earlier quoted context omitted.

Google had done extensive studies[1]. There is roughly 3% chance of error in RAM per DIMM per year. That doesn't justify buying ECC if you have just one personal computer to worry about. However if you are in data center with 100K machines each with 8 DIMM, you are looking at about 6K machines experiencing RAM errors each day . Now if data is being replicated then these errors can propogate corrupted data in unpredic…

That data set covers 2006-2009 and the ram consisted of 1-4GB DDR2 running at 400-800 MB/S. Back when 4GB was considered a beefy desktop, consumers could get away with a few bit-flips during the lifetime of the machine. Now my phone has that much RAM and a beefy desktop consists of 16-32 GB of RAM running at 3GB/s. It's time we start trading off the generous speed and capacity gains for a some error correction.

Note that the error rate is not proportional to the amount of RAM, it is proportional to the physical volume of the ram chips. (The primary mechanism that causes errors are highly energetic particles hitting the chips, the chance that this happens is proportional to the volume of the chips.) This means that the error rate per bit goes down as density goes up.

Re: Should I buy ECC memory? (2015)

#180

Post by tsukikage »

No-one's mentioned it yet, but we're in a post-Rowhammer world and ISTM this is relevant to the discussion: while not all non-ECC DIMMs are susceptible, the cheaper ranges generally are, and if your purchasing decisions are driven by hardware cost, that's probably what you'll end up with. Corruption due to malice is a rather different beast to corruption due to random cosmic rays...
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