Hacker News Reader

Comment by ChuckMcM | Hacker News Reader

Once again, I pine for ECC memory on my Laptop. I know you can get ECC SODIMMS, I got 16GB worth for a Supermicro ITX motherboard. And while the paper talks about multi-bit errors getting through ECC (which is certainly possible with enough flips) single flips causing alerts and double flips causing halts would really get your attention that something bad was happening. As opposed to silently sitting there while my memory is shredded.

View on HN

Intel cripples their "consumer grade" processors by locking out the ECC DRAM interface. This forces server vendors to buy "server grade" processors. There, you get all the good error-correction stuff.[1] The fraction of die space devoted to these features is small; there's no reason they couldn't be provided on all x86 family CPUs. It's purely a market positioning thing.

AMD leaves the ECC hardware enabled on most of their parts.

[1] http://www.intel.com/content/dam/www/public/us/en/documents/...

Not just laptops! SQL Azure doesn't use ECC memory[1], which might suggest the rest of the Azure platform doesn't, either. I haven't found citations for AWS using ECC, so perhaps they don't. Maybe this could be used to break out of VMs on those platforms.

1: https://social.msdn.microsoft.com/Forums/azure/en-us/84000f7... (I remember I asked about Windows Azure, but my posting clearly says SQL Azure, so perhaps it's a different hardware platform.)

This may be just speculation, as the memory density in cloud hosts is rarely possible with non-ECC memory. I've found that when purchasing RAM for systems, it's fairly common for server and multi-rank to imply ECC, although I've had to look at product sheets to verify that.

Now, I could be wrong, but it would be quite a surprise to find out that any of the cloud services are not using ECC. I suspect they all are, but they don't advertise it.

Well I mean I asked in that thread, and MS replied stating they simply do not need ECC. I quoted a line from Google's study on memory errors, and Azure replied: "In our scenario, we have not seen bit error rates that align with the quote you mention".

I suppose I could just spin up a 56GB instance and let it run a memtest for a week and see, right?

SQL Azure probably need less RAM than Windows Azure VMs on the other hand.

If I understand correctly, Intel doesn't even ship a consumer CPU (i.e., a non-Xeon) that supports ECC. (Don't know about AMD.)

It used to be the case that all AMD CPUs supported ECC back in the AM2/AM3 era, apparently this may no longer be true though. Not all motherboards bothered to route the extra traces required for it and include BIOS support though.

All AMD FX and Opteron CPUs support ECC. The APUs do not. For the CPUs that support ECC, it is still up to the motherboard manufacturer to support it on their end as well.

> Intel doesn't even ship a consumer CPU (i.e., a non-Xeon) that supports ECC.

Not true - there are some Atoms that do, but they're targeted at NAS type uses. It is the case you can't get Core-series processors with ECC.

AMD used to offer very broad support for ECC, but data integrity clearly didn't win market share.

This is no longer true either. Intel has consumer desktop Celeron, Pentium, and i3 series chips that support ECC.

The i3's in particular are fairly popular with FreeNAS users.

http://ark.intel.com/search/advanced?s=t&SocketsSupported=FC...

data integrity clearly didn't win market share

It requires more expensive, compatible DRAM right? Knowing that, it shouldn't really be super surprising. Enabling it on die is just one piece of the equation.

The problem is that if you say "fast, cheap, reliable, pick two" people will pick "fast" and "cheap". Even people who might ordinarily worry about whether their workstation is silently corrupting their data.

i3 are dual cores that support ECC, aimed at NAS and the like (hence mini ITX boards with ECC SODIMMs). But you still need an explicit workstation chipset/mobo to support it.

i5 and i7 have no ECC because there are equivalent Xeons. At this level "Xeon" is just branding implying features like ECC, and it doesn't automatically mean expensive - a single socket non-E (LGA1150) Xeon build costs only a little more (~20%) than consumer cpu/mobo/ram (although there's better sales on the consumer stuff).

Heck, if you are buying a non-K series i7, the equivalent Xeon E3 will probably be cheaper by a few dollars.

it's also very possible it's not as fast. consult benchmarks first, as usual.

I don't think ECC will help. Where you can flip one memory bit, you can flip two consequently.

It will help, two bit errors are not corrected, though. The system will be rebooted and and an error should be logged.

I don't think laptops have SODIMM memory these days.

Sadly true, the 'thin is in' crowd is more often than not soldering in the memory.

I bought one two weeks ago that has two SODIMM slots.

Depends on the laptop. I have bought two laptops in the past 14 months, a $2000 ThinkPad and a $600 Acer. Both came with 4GB soldered on and a single free SODIMM.

(On a different note: the ThinkPad maxes out at 8GB and the Acer at 12GB, whereas previous generations went up to 16GB at least. Intel intentionally nerfed Haswell and newer core i's, presumably to push their Xeons on more people)

Intel intentionally nerfed Haswell and newer core i's, presumably to push their Xeons on more people

Really? I think the latest Haswell can go to 16GB just fine if there are two SO-DIMM slots.

There are 16GB SODIMMs, so why isn't Intel supporting those? The company that makes them claims this is purely on Intel/OEMs.

1: http://www.intelligentmemory.com/dram-modules/ddr3-so-dimm/

Update: Oh wow, the new Broadwell chips do support them. So maybe the new ThinkPad X250 isn't so useless after all! This is great news if true.

Intelligent Memory's are probably too expensive for the normal laptop market. Micron claims to be sampling them now: http://www.micron.com/products/dram-modules/sodimm/DDR3%20SD...

They're supposed to be priced around $350 or so, at least that's what I see from last year. How is that too expensive? An X series ThinkPad is like $2300+ with a good config. Adding another few hundred so I can have a decent amount of RAM sounds like a no-brainer.

(Or, Lenovo could put IBM engineering in charge and figure out how to get 2 slots back on the X series.)

I am thinking of the two 16GB DIMM setup, sorry.

Be careful... the 5th gen Intel CPUs can NOT run with standard 16GB modules. There is a technical issue which causes instabilities with 16GB modules, except if the modules are specially made to cover this issue. The Intelligent Memory modules do that.

I wonder if this issue is actually in hardware or just in the MRC.

http://techreport.com/discussion/27928/intel-xeon-d-brings-b... mentions 16GB per UDIMM.

Reply on news.ycombinator.com