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Should I buy ECC memory? (2015)

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Re: Should I buy ECC memory? (2015)

#111

Post by __jal »

dom0 wrote: post #50
__jal wrote: post #33

Earlier quoted context omitted.

History. The ZFS folks, back when, were the only folks making much noise about the association between non-ECC RAM and corrupt data landing on disk. The truth is, if you care about the notion that your disk should return the same data that software thought it was writing, you should use ECC with any file system. But The ZFS folks made noise about the issue, I think lots of people assumed the reason was that there was…

> should return the same data that software thought it was writing Hint: In an OS using a page cache (= every OS ) I/O errors are not reliably propagated to applications unless they explicitly sync their dirty pages.

I'm aware of that, but I'm not sure what I'm supposed to take away from it in this context.

Re: Should I buy ECC memory? (2015)

#112

Post by blackflame7000 »

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 bit flip could somehow make the HTTP server vulnerable and able to compromise the network however that risk is impossibly small. If we take IBMs estimation that a bit flip occurs at an approximate rate of (3.7 × 10-9) bytes/month and then divide it by the number of bytes in the system you can see that the odds of randomly corrupting a byte in memory that triggers a vulnerability is too small.

Re: Should I buy ECC memory? (2015)

#113

Post by nine_k »

rascul wrote: post #87
loeg wrote: post #72

Earlier quoted context omitted.

> 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. How do you make that leap?

A cost/benefit analysis for a system where non critical operations are performed would seem to favor the non ECC memory. I suspect this is the case for the majority of people who have computers for their personal use, without taking into account that they might not even be aware such a thing exists. Although, I haven't compared ECC prices lately.

Your game machine can live without ECC.

Your NAS should better have it, though.

Re: Should I buy ECC memory? (2015)

#114

Post by tdb7893 »

sitkack wrote: post #109
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…

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

Re: Should I buy ECC memory? (2015)

#115

Post by yuhong »

binarycrusader wrote: post #93
snuxoll wrote: post #45

Earlier quoted context omitted.

AFAIK all of the Xeon chips support ECC, every Xeon E3 chip (which uses the desktop socket) I've looked at includes it.

Sorry, I was a little obtuse. What I was inferring was that historically, only higher-priced server chips from Intel had ECC support. In 2013, Intel launched the v3 lower-end Xeon E3s server chips that were closer to the price of the consumer Intel chips and offer ECC with comparable clock speeds. Of course, all of those only have 4 cores instead of 8. Yes, all of the E3s support ecc, but Xeon's didn't always support…

There was the Xeon 3400 even before that. Trivia: it supported registered ECC, but only x8 chips and not x4.

Re: Should I buy ECC memory? (2015)

#116

Post by gizmodo59 »

blackflame7000 wrote: post #15

Altitude also plays a factor in random memory corruption. From the wikipedia article on ECC Ram, "Hence, the error rates increase rapidly with rising altitude; for example, compared to the sea level, the rate of neutron flux is 3.5 times higher at 1.5 km and 300 times higher at 10–12 km (the cruising altitude of commercial airplanes).[3] As a result, systems operating at high altitudes require special provision for r…

I wonder if this has anything to do with Microsoft's plans to build an underwater data center.

Re: Should I buy ECC memory? (2015)

#117

Post by wtallis »

binarycrusader wrote: post #93
snuxoll wrote: post #45

Earlier quoted context omitted.

AFAIK all of the Xeon chips support ECC, every Xeon E3 chip (which uses the desktop socket) I've looked at includes it.

Sorry, I was a little obtuse. What I was inferring was that historically, only higher-priced server chips from Intel had ECC support. In 2013, Intel launched the v3 lower-end Xeon E3s server chips that were closer to the price of the consumer Intel chips and offer ECC with comparable clock speeds. Of course, all of those only have 4 cores instead of 8. Yes, all of the E3s support ecc, but Xeon's didn't always support…

Xeon has implied ECC support for as long as Xeons have had integrated memory controllers, which is just a generation or two further back than the first Xeon E3 product line. Before that, ECC support was a function of the northbridge.

Re: Should I buy ECC memory? (2015)

#118

Post by SolarNet »

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!

Some macs do use ECC memory (specifically some of the most popular varieties, like the Mac Pro) which is probably why you saw lower numbers on bit squatted domains.

Re: Should I buy ECC memory? (2015)

#119

Post by rorosaurus »

gizmodo59 wrote: post #116
blackflame7000 wrote: post #15

Altitude also plays a factor in random memory corruption. From the wikipedia article on ECC Ram, "Hence, the error rates increase rapidly with rising altitude; for example, compared to the sea level, the rate of neutron flux is 3.5 times higher at 1.5 km and 300 times higher at 10–12 km (the cruising altitude of commercial airplanes).[3] As a result, systems operating at high altitudes require special provision for r…

I wonder if this has anything to do with Microsoft's plans to build an underwater data center.

If I remember correctly, that research venture was mostly due to the potential of easy heat exchange and "free" energy via geothermal/tidal. Now that you mention this, though, it's clear that such a datacenter would also be naturally shielded from many things!

Re: Should I buy ECC memory? (2015)

#120

Post by TheSmiddy »

colanderman wrote: post #92
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…

> There is roughly 3% chance of error in RAM per DIMM per year. […] with 100K machines each with 8 DIMM, you are looking at about 6K machines experiencing RAM errors each day. Can you work out the math? I don't follow it. 3%×100K×8÷365=66 per day by my reasoning…

they've multiplied by 3 instead of 0.03
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