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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 persona
by sytelus 10y ago
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 unpredictable unexplainable way even when there are no bugs in your code! For example, you might encounter your logs containing bad line items which gets aggregated in to report showing bizarre numbers because 0x1 turned in to 0x10000001. You can imagine that debugging this happening every day would be huge nightmare and developers would end up eventually inserting lot of asserts for data consistency all over the places. So ECC becomes important if you have distributed large scale system.
1: http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf
- loeg 10y ago> 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?
- delish 10y agoI'd like to know this, too. I am guessing it's because, if RAM errors increase linearly with the number of computers, then RAM errors will be a greater and greater proportion of total errors. This assumes other kinds of errors don't scale linearly. Someone looking through logs is looking for errors, they'd like to find fixable logic errors, not inevitable RAM errors.
- tertius 10y agoBecause the market.
- user5994461 10y agoIt's an inappropriate leap. Consumers should have ECC memory too. However the consumer market has long decided to settle for ECC nowhere and cheap everywhere. ECC hardware comes at premium option that can easily be +100%. You need support in the memory, the motherboard and the CPU. Given the price difference, personal computers will have to live with the memory errors. People will not pay double for their computers. Manufacturers will not sacrifice their margin while they can segment the market and make a ton of money off ECC.
- michaelmrose 10y agoAmd has modestly priced hardware that supports ecc
- rfrank 10y agoWas that the case before Ryzen? I know their new CPUs support ECC, but I'm not sure for earlier generations.
- yuhong 10y agoI think it was common for AM3 for example too.
- qb45 10y agoECC is officially supported by all AM2/3(+) CPUs and AFAIK all corresponding motherboards from ASUS. As in, you have it guaranteed on the spec sheet. There are also reports of BIOS support in some boards which don't have ECC advertised. And you can try to enable it in the OS even without BIOS support, though some level of hardware support is still necessary. As Linux documentation puts it: "may cause unknown side effects" :)
- dagw 10y agoIt was technically supported by the hardware, but not by many motherboard and BIOS's.
- loeg 10y agoYep.
- yuhong 10y agoBristol Ridge does support ECC BTW, but one problem is that you can't use ECC with x16 chips (because ECC is 72-bit), so with 8GB of RAM and 8Gbit chips you have to choose between non-ECC/ECC single channel with x8 chips and non-ECC dual channel with x16 chips. 4Gbit don't have this problem but will become obsolete especially when 18nm ramps up, and while DRAM prices should decline when that happens...
- rascul 10y agoA 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.
- nine_k 10y agoYour game machine can live without ECC. Your NAS should better have it, though.
- flamedoge 10y agoProbably assumptions about uses of PC. I'd imagine most of bits are media related.
- pseudalopex 10y agoThat's a 3% per DIMM per year chance of at least one error. Most memory faults are persistent and cause errors until the DIMM is replaced. Also, the error rate was only that low for the smallest DDR2 DIMMs.
- colanderman 10y ago> 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…
- TheSmiddy 10y agothey've multiplied by 3 instead of 0.03
- sitkack 10y agoI 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.
- tdb7893 10y agoHow 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
- gh02t 10y agoIt'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.
- fgonzag 10y agoGood thing ryzen supports ECC OBO. Just waiting on motherboard support for it.
- bitJericho 10y agoIf you're not worried about certain chip features and power draw, last gen server equipment is very cheap.
- sitkack 10y agoLots of Ryzen motherboards support ECC. http://www.asrock.com/mb/AMD/X370%20Killer%20SLIac/#Specification http://www.asrock.com/mb/AMD/X370%20Killer%20SLIac/#Specific...
- lomnakkus 10y agoI 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(?).)
- indolering 10y agoThat 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.
- Tuna-Fish 10y agoNote 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.
- krzyk 10y agoWouldn't it go up if the density increases? If the particle hits the chip there are more bits at the place where the particle hits. So while the chance of hit is lower (per GB), if it hits its effect will be higher (more bits flipped).
- apoorvkumar 10y agoAn alpha particle for instance is atleast an order of magnitude smaller than smallest transistor. The maximum damage it can do is effectively 1 bit.
- apoorvkumar 10y agoActually these high energy particles tend to be order of size of proton or less - so make that 6 orders of magnitude smaller than smallest transistor.
- krzyk 10y agoAlpha particle won't penetrate that far, it will be stopped at the building level, or at the enclosure. Piece of paper blocks it. Beta and gamma are the ones that can do damage (not sure about beta), and gamma can pass through the entire chip, so it can hit multiple transistors, depends on the angle and the way they are located.
- amelius 10y agoThis makes me wonder how banks deal with this issue.