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Should I buy ECC memory? (2015)

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Re: Should I buy ECC memory? (2015)

#31

Post by justin66 »

hashhar wrote: post #23
ddingus wrote: post #5

Yes. Bit errors are uncommon and range from benign to crash. Your storage has them, memory has them, network has them. Non error correcting memory very significantly increases risk. And this is the kind of risk you don't notice, until you do and when you do, it's often subtle, insidious, impossible to track down. Servers absolutely. It's debatable on desktop, but we have huge RAM now. Might as well error correct. The…

I won't bother on a desktop. I've been using 4 machines for the last 17 years with storage varying from 10GB to 2TB and RAM varying from 128MB to 16GB and haven't personally seen any kind of data corruption in motion (or at rest for that matter). Only had 2 mechanical drives fail (though predictably). ECC is costly. The memory modules itself and the board required to support it properly.

> haven't personally seen any kind of data corruption

How would you know? Unless your computer use has been literally trouble-free (and all your archived data has been verified for correctness somehow), you can't know that none of your glitches over the past 17 years has been due to memory errors.

Re: Should I buy ECC memory? (2015)

#32

Post by xenadu02 »

hashhar wrote: post #23
ddingus wrote: post #5

Yes. Bit errors are uncommon and range from benign to crash. Your storage has them, memory has them, network has them. Non error correcting memory very significantly increases risk. And this is the kind of risk you don't notice, until you do and when you do, it's often subtle, insidious, impossible to track down. Servers absolutely. It's debatable on desktop, but we have huge RAM now. Might as well error correct. The…

I won't bother on a desktop. I've been using 4 machines for the last 17 years with storage varying from 10GB to 2TB and RAM varying from 128MB to 16GB and haven't personally seen any kind of data corruption in motion (or at rest for that matter). Only had 2 mechanical drives fail (though predictably). ECC is costly. The memory modules itself and the board required to support it properly.

The only reason ECC is costly is because Intel has a monopoly on the desktop/server chip market and they refuse to deploy ECC to consumer chips. The hardware is there, it's just fused disabled.

If ECC were only the cost premium and we assumed a linear relationship then it should cost about 1/8 more than non-ECC DRAM. Unfortunately Intel's decisions have knock-on effects that ripple through the rest of the market.

IIRC I saw somewhere that JDEC expects a future standard will require ECC to get acceptable error rates for all memory. At that point Intel won't have any choice.

Re: Should I buy ECC memory? (2015)

#33

Post by __jal »

mikeash wrote: post #24
static_noise wrote: post #10

Earlier quoted context omitted.

Do you use ZFS? If no then you should use ECC memory. Now the half truth becomes full-truth.

I don't get this association between ZFS and ECC. The recommendation to use ECC with ZFS basically comes down to "all that fancy data integrity checking that ZFS does won't protect you from memory errors, so you'll effectively lose that feature." Are you OK with silent data corruption? If so, don't bother with ECC. If not, use it.

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 something special about ZFS that needed it, and now you have something sort of like an urban legend.

Re: Should I buy ECC memory? (2015)

#34

Post by muro »

mikeash wrote: post #19
VA3FXP wrote: post #9

Depends on what you are doing. ZFS storage servers: Hell yes High-value data in my DB? Hell yes email server: Nope super cool gaming rig: Nope * Cluster: Hell yes General office workstation: maybe. I don't have the budget for 20 redundant copies. I do have the budget for slightly more expensive RAM. Especially on my ZFS storage arrays. ECC memory is like Insurance. You hope you never need it. One real downside that I…

I agree on gaming, but e-mail often contains important information that I wouldn't want to suffer from random corruption.

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

Re: Should I buy ECC memory? (2015)

#35

Post by awqrre »

rocqua wrote: post #13
VA3FXP wrote: post #9

Depends on what you are doing. ZFS storage servers: Hell yes High-value data in my DB? Hell yes email server: Nope super cool gaming rig: Nope * Cluster: Hell yes General office workstation: maybe. I don't have the budget for 20 redundant copies. I do have the budget for slightly more expensive RAM. Especially on my ZFS storage arrays. ECC memory is like Insurance. You hope you never need it. One real downside that I…

There is a hidden cost of ECC with regards to the chipset. None of the cheap chipsets support it, so on any home build, it's going to be expensive.

Not only cost, it can also be harder to find a motherboard with ECC support and with all the components/inputs/outputs that you would want in a desktop computer.

Re: Should I buy ECC memory? (2015)

#36

Post by dogma1138 »

rocqua wrote: post #13
VA3FXP wrote: post #9

Depends on what you are doing. ZFS storage servers: Hell yes High-value data in my DB? Hell yes email server: Nope super cool gaming rig: Nope * Cluster: Hell yes General office workstation: maybe. I don't have the budget for 20 redundant copies. I do have the budget for slightly more expensive RAM. Especially on my ZFS storage arrays. ECC memory is like Insurance. You hope you never need it. One real downside that I…

There is a hidden cost of ECC with regards to the chipset. None of the cheap chipsets support it, so on any home build, it's going to be expensive.

There are cheap chipsets that support the entry level workstation ones from Intel you can get a motherboard for 65$ with ECC support you don't need to go to x99.

I have a few home storage servers running on the low end Pentiums with ECC support on these.

Re: Should I buy ECC memory? (2015)

#37

Post by dogma1138 »

binarycrusader wrote: post #17
rocqua wrote: post #13

Earlier quoted context omitted.

There is a hidden cost of ECC with regards to the chipset. None of the cheap chipsets support it, so on any home build, it's going to be expensive.

Not true with Ryzen, as long as you find unregistered ECC acceptable. Somewhat not true with Intel, as some of the lower end Xeons now support it.

Only ASROCK currently has BIOS/UEFI support for ECC.

Re: Should I buy ECC memory? (2015)

#38

Post by lomnakkus »

olavgg wrote: post #26

Can people here please stop posting that ZFS needs ECC memory. Every filesystem, with any name like FAT, NTFS, EXT4 runs more safe with ECC memory. ZFS is actually one of the few that can still be safer if you don't run with ECC memory. Source: Matthew Ahrens himself: https://arstechnica.com/civis/viewtopic.php?f=2&t=1235679&p=...

Indeed. It's true that the data may be corrupted before hitting any disk[1], but once it has hit the disks (>1), it's extremely unlikely that you'll ever hit a similar bit error where it'll mistakenly choose the wrong disk block to recover from.

The main point of e.g. ZFS or Btrfs checksumming is that a) at least it isn't getting worse, and b) I can tell if it's getting worse.

[1] ... but if the bits are not generated by the machine that actually saving to disk, how do you know they weren't corrupted along the way? The number of people who religiously check PGP signatures/SHA256sums or whatever is miniscule.

Re: Should I buy ECC memory? (2015)

#39

Post by X86BSD »

olavgg wrote: post #26

Can people here please stop posting that ZFS needs ECC memory. Every filesystem, with any name like FAT, NTFS, EXT4 runs more safe with ECC memory. ZFS is actually one of the few that can still be safer if you don't run with ECC memory. Source: Matthew Ahrens himself: https://arstechnica.com/civis/viewtopic.php?f=2&t=1235679&p=...

It's not the that it NEEDS it, it's that if you DONT use it you are introducing potential data errors into an otherwise checksummed data path. Which would completely negate the rest of the path.

Re: Should I buy ECC memory? (2015)

#40

Post by dogma1138 »

mikeash wrote: post #24
static_noise wrote: post #10

Earlier quoted context omitted.

Do you use ZFS? If no then you should use ECC memory. Now the half truth becomes full-truth.

I don't get this association between ZFS and ECC. The recommendation to use ECC with ZFS basically comes down to "all that fancy data integrity checking that ZFS does won't protect you from memory errors, so you'll effectively lose that feature." Are you OK with silent data corruption? If so, don't bother with ECC. If not, use it.

Because with ZFS bit rot can be cumulative, with most file systems a memory error will corrupt a file if the format can't handle errors, with ZFS overtime the entire volume can get corrupted especially when you are doing recovery or expansion, even in normal operation data is moved around quite a bit. For them most part with other common file systems when a file is written it stays there even in RAID.
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