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Should I buy ECC memory? (2015)

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Re: Should I buy ECC memory? (2015)

#191

Post by krzyk »

apoorvkumar wrote: post #187
krzyk wrote: post #181

Earlier quoted context omitted.

Wouldn'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).

An alpha particle for instance is atleast an order of magnitude smaller than smallest transistor. The maximum damage it can do is effectively 1 bit.

Alpha 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.

Re: Should I buy ECC memory? (2015)

#192

Post by mafro »

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.

I just last week bought an ASRock C236 WSI [1] for £170. 8GB of ECC RAM was £80. Granted that five years ago I needed to pay more than twice that amount - so I skipped the ECC :p

[1] http://asrockrack.com/general/productdetail.asp?Model=C236%2...

Re: Should I buy ECC memory? (2015)

#193

Post by mafro »

awqrre wrote: post #35
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 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.

See sibling comment: I just picked up an ASRock C236 WSI

Re: Should I buy ECC memory? (2015)

#194

Post by ddingus »

Zardoz84 wrote: post #184
ddingus wrote: post #151

Earlier quoted context omitted.

If you want to be sure it's right, yes. Here is the thing: Without ECC, or even simple parity on the RAM, the CPU cannot validate a data transfer. In the 90s, a place I worked for had a server running non parity, non ECC RAM. That machine was fast and cheap. But it would demonstrate the most bizarre problems, from time to time. A fresh OS install would fix it. Then a year or so, off the farm again. I saw no error cor…

> I did put that box on my personal network, and under Linux (was win NT before), seemed fine. In the syslog, after a year, there were various kernel messages, each recovered, but there was something to recover from... Win NT would blue screen a lot. That's different today with better kernel software from Microsoft, but the point is no error correction comes with no real way to understand where some trouble may have…

Yeah, good times back then. :D

I ran a Win, IRIX, Linux network in my cube. Had, like 5 machines all doing various things.

Here's another similar thing:

Someone handed me a 33mhz SGI Indigo. "What can we do with it?"

I compiled a little program called "amp" to play Mp3 files, just wondering...

That thing could actually play 256kbps files, shared over NFS, while also offering a desktop. Someone else made a little app that could select tunes, start, stop. I could tell the bitrate based on the CPU load.

Put that and the SGI mixer on the screen, and it was the department tunes. I took it home at one point, where it continued to do that task well into the 00s

CPU utilization was 95 percent, but ran all day long for weeks, not a stutter.

The general point being, a UNIX, Linux could do magic on trash, old, odd, slow, gear and not miss a beat.

An old Pentium 90, running RH 5.2 served up the web pages while also acting as firewall and doing mail.

That thing was literally a dumpster dive. It had NT on it, and just would not run no matter what. Linux did, with a stream of kernel chatter in syslog. A console window (tail -f) showed this stream of scary looking text the whole time. crazy!

That was a stunt. Worked. Should not have. Did a few months duty, the real machine queued up, just in case.

Re: Should I buy ECC memory? (2015)

#195

Post by agentgt »

krzyk wrote: post #181
Tuna-Fish wrote: post #179

Earlier quoted context omitted.

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.

Wouldn'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).

It is an interesting question but I think the parent poster did not mean density in the pure physical sense.

That is more memory but less mass which is not physical density. Also I am not sure if gamma rays need to just hit the physical bits to mess things up. If is the case where other things can be hit then it seems surface area might have high correlation but probably not.

I don't know what the answer is but I would imagine that the error rate would be the same percentage assuming orientation is kept the same.

Of course if you are going at extreme macro sense (think Asimov last question computers [1]) then density absolutely probably plays role as gravity starts to cause enormous amount of collisions. This actually happens in stars and is why photons take a long time to escape from the star as well as the edge of black holes where collisions are happening extremely frequently.

[1]: http://multivax.com/last_question.html

Re: Should I buy ECC memory? (2015)

#196

Post by usrusr »

intrasight wrote: post #164

I am typing this (finally!) on my new desktop build. I did mull over the decision for a while but finally went with Xeon and ECC. So the memory cost more - perhaps even twice as much - so what? I use my computer pretty heavily for my work - with several VMs running at a time. If ECC saves me a headache once a year, it will have paid for itself. If it never provides ANY benefit I will still not regret the peace of min…

The parameters of the desktop ECC decision have changed massively with today's glacial replacement cycles. Today you make a one time payment for many years of avoided headaches and peace of mind, whereas back then any sign of unreliability would have been a welcome excuse for a cheap upgrade.

Re: Should I buy ECC memory? (2015)

#197

Post by lmm »

tscs37 wrote: post #170
thraway2016 wrote: post #75

Earlier quoted context omitted.

Conventional legal mechanisms against your home server cabinet can be handled via full disk encryption and a reed switch on your cabinet door connected to your power strip.

Sounds fun until you have to open your cabinet door for legit reasons like swapping a faulty hard drive in your RAID array.

Huh? If you're going to swap a faulty hard drive you want to power off anyway.

Re: Should I buy ECC memory? (2015)

#198

Post by koffiezet »

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=...

ZFS is not the cheap option, it was never intended to be - so why bother skimping on ECC? If you're worried about ECC prices - ZFS is probably not for you.

It's not that you need ECC for ZFS, but when you're at a point where you're willing to throw money at a storage system where ZFS makes sense, the extra cost of ECC is minuscule. The most expensive hardware requirement of ZFS is that you need disks of the same size anyway, which means you're not just throwing a random amount of disks together, and if you want to expand, you need to add another full zpool, or replace disks one by one.

On my home NAS, the difference was about 120 EUR for 32GB (80eur/dimm vs 50eur/dimm), on a grand total of over 2500 EUR. One of the reasons for choosing ZFS was storage reliability, and then skimping out on ECC is a imho a bit silly.

Re: Should I buy ECC memory? (2015)

#199

Post by tscs37 »

lmm wrote: post #197
tscs37 wrote: post #170

Earlier quoted context omitted.

Sounds fun until you have to open your cabinet door for legit reasons like swapping a faulty hard drive in your RAID array.

Huh? If you're going to swap a faulty hard drive you want to power off anyway.

I hotswap drives all the time, it's not a problem and makes a harddrive swap a 30 second task instead of a 10 minute task and doesn't incur downtime either.

Re: Should I buy ECC memory? (2015)

#200

Post by VA3FXP »

toast0 wrote: post #90
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…

You should be getting MCA (machine check architecture?) notifications in syslog/dmesg if there are ECC correctable errors, and an MCE (machine check exception) on the console for uncorrectable error, based on my experience with SuperMicro xeon servers running FreeBSD. A lot of our servers see a few correctable errors once in a while, and it doesn't affect the usability of the system; but sometimes the number of corre…

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