You assert that ECC RAM being necessary for ZFS is just a myth but provide no justification for why that is untrue.

Is it not the case that if you don't have ECC memory, ZFS could end up writing a checksum that does not match the data if you get a bitflip in just the right (wrong) spot?

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Confiks an hour ago | parent | next [-]

Yes, indeed. ECC RAM is better than non-ECC RAM, also for ZFS.

The myth, popularized by a notorious thread on the TrueNAS forums [1], is specifically that ZFS requires ECC RAM, and will do worse than other filesystems without it, because scrubbing will multiply a single bitflip into a failed pool.

A ZFS core developer says that that isn't the case [2]. Here's some more reasoning [3], also about many other myths.

[1] https://www.truenas.com/community/threads/ecc-vs-non-ecc-ram...

[2] https://news.ycombinator.com/item?id=18480016

[3] https://kldload.com/zfs-wiki/myths

	▲	StrangeWill 10 minutes ago \| parent \| next [-]
		The only hangup with the myth "debunking" is that the point is that the corruption doesn't happen to a per-disk buffer, but to the in-flight data before it's persisted to your stripe. Which means all copies of the data will be corrupted. This can be anything from an irrecoverable file to complete filesystem corruption. But generally, yeah, not any more dangerous than any other filesystem, and ECC used to be cheap so it was a no-brainer, you should have backups anyway TBH if we're being honest about storage resiliency. What has been debunked is the "scrub of death" issue, on a scrub a bad bit flip would cause an error, which would be copied over with good data -- well it was technically good before. It would be statistically difficult to have a fault on a read, then a clean read, then a second bit flip destroying the data.
	▲	dijit 24 minutes ago \| parent \| prev \| next [-]
		Usually if you’re using a NAS you don’t want to lose data, ZFS is not significantly more sensitive than everything else. But everything is actually quite sensitive. We’ve accepted lack of ECC because Intel decided it would be a product line differentiator, and serious customers who didn’t want random crashes or to lose data would buy chips with ECC. It’s actually less of an issue these days because DDR5 has (by spec) some in-line ECC; won’t help with multi-bit errors but its an improvement on what came before.
	▲	magicalhippo 34 minutes ago \| parent \| prev [-]
		Updated link to the post from Matt Ahrens here[1], which is one of the ZFS creators[2] not "just" a core developer. [1]: https://arstechnica.com/civis/threads/ars-walkthrough-using-... [2]: https://en.wikipedia.org/wiki/ZFS#2004%E2%80%932010:_Develop...

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naturalmovement an hour ago | parent | prev [-]

> You assert that ECC RAM being necessary for ZFS is just a myth but provide no justification for why that is untrue.

ZFS without ECC is no more risky than any other file system / software RAID without ECC.

As no one owes you an explanation, it would take you five seconds to Google this and discover:

1. It's been disproven, with one of the original ZFS developers chiming in.

2. The original source of the rumor was a forum post that somehow became canon.