101–110 of 237 posts
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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.
An old article from DJB worth perusal: http://cr.yp.to/hardware/ecc.html It's also worth noting that not all ECC (SECDED) is created equal: ChipKill™ and similar might not survive physical damage because of likely shorts of the data bus but a single malfunctioning chip producing/experiencing higher hard error rate is possible from which to recover. Also, it'd be really cool if some shop a-la BackBlaze blogged about l…
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Either way, it'd be fine on SSDs, then?
Hm? As long as the error correction technology on your chosen SSD of choice stands up, I guess... yes? What, exactly, are you asking?
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> If you look through the source code & postmortems from that era of Google, there are all sorts of nasty hacks and system design constraints that arose from the fact that you couldn't trust the bits that your RAM gave back to you. Details of this would be very interesting, but obviously I understand if you cannot provide such details due to NDAs, etc. I mean, I can imagine a few mitigations (pervasive checksumming,…
You need ECC /and/ pervasive checksumming. There are too many stages of processing where errors can occur. For example, disk controllers or networks. The TCP checksum is a bit of a joke at 16 bits (it will fail to detect 1 in 65000 errors), and even the Ethernet CRC can fail - you need end to end checksums. http://www.evanjones.ca/tcp-and-ethernet-checksums-fail.html
Personally, I'm a bit of a hoarder of data, but honestly, if X-proportion of that data were to be lost... it probably wouldn't actually affect my life substantially even though I feel like it would be devastating.
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> If you look through the source code & postmortems from that era of Google, there are all sorts of nasty hacks and system design constraints that arose from the fact that you couldn't trust the bits that your RAM gave back to you. Details of this would be very interesting, but obviously I understand if you cannot provide such details due to NDAs, etc. I mean, I can imagine a few mitigations (pervasive checksumming,…
You need ECC /and/ pervasive checksumming. There are too many stages of processing where errors can occur. For example, disk controllers or networks. The TCP checksum is a bit of a joke at 16 bits (it will fail to detect 1 in 65000 errors), and even the Ethernet CRC can fail - you need end to end checksums. http://www.evanjones.ca/tcp-and-ethernet-checksums-fail.html
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Hm? As long as the error correction technology on your chosen SSD of choice stands up, I guess... yes? What, exactly, are you asking?
My thought was "reading SSDs doesn't degrade them, so there's no disadvantage to constant scrubbing." Unless I've misunderstood what you mean by "reading."
(That's where that came from, draw your own conlusions :).)
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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 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. That doesn't justify buying ECC if you have just one personal computer to worry about. How do you make that leap?
While I was at Google, someone asked one of the very early Googlers (I think it was Craig Silverstein, but it may've been Jeff Dean) what was the biggest mistake in their Google career, and they said "Not using ECC memory on early servers." If you look through the source code & postmortems from that era of Google, there are all sorts of nasty hacks and system design constraints that arose from the fact that you could…
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…
Yes. Everybody reading this should use ECC RAM, and non-ECC RAM should be called "error-propagating RAM". Random bit flips aren't cool, and they happen regularly. Most computers that have ECC RAM can report whether errors happen. I see them at least once a year or so. For instance, here are 2 ECC-correctable memory errors that occurred just last month. Cosmic rays? Fukushima phantom? Who knows. You'll never know why…