Hello, I know this ECC vs. Non-ECC topic it is a very sensitive one here in the forum. But I would like to understand how a scrub exactly works on ZFS to make my own judgement if ECC is really needed or not (I had a debate with a colleague some days ago, I argueg for ECC, he argued against). Let’…

[image] thomas-hn: In this case data could get lost (as ZFS thinks the data is faulty), even that the data on the drives might be fine and only the RAM has an issue. You’d get ZFS errors complaining about checksums not matching, but because the checksums don’t match, ZFS won’t touch anything …

The scenario is commonly referred to the ZFS Scrub Of Death. Though generally described with non-permanent RAM errors. It is in someways a Myth of Epic proportions. But, my own opinion is that under extremely odd and unusual cases, non-ECC RAM could corrupt a pool during a scrub. My own take is th…

We’ve had ONE actual report of a Scrub of Death: [image] ECC memory vs Non-ECC memory - Poll! TrueNAS General I used to come down on the side of ECC being optional, but had a RAM stick fail in my parents server that would flip a certain bit so consistently that it not only…

As the survivor of said Scrub of Death (which I also thought to be implausible previously), I want to note the stick of RAM was very bad. It would only take seconds in MemTest before errors started appearing. Without ECC, and with most of the memory on that server consumed by ARC, I had no obvious …

This might be an interesting read: https://jrs-s.net/2015/02/03/will-zfs-and-non-ecc-ram-kill-your-data/

[image] DAVe3283: As the survivor of said Scrub of Death (which I also thought to be implausible previously), I want to note the stick of RAM was very bad. It would only take seconds in MemTest before errors started appearing. Thank you for clarifying that detail. I had minor doubts that you…

Anyone who claims that has never dealt with printers.

This discussion made me wonder about one of my file servers that does not have ECC memory and actually has a cheap consumer motherboard too. I have never encountered a ZFS error in my limited experience with TrueNAS (~3 years). Would it be possible to set an alert for such ZFS errors that may occur …

Is your data more valuable than the price differential between ECC and non-ECC? If so, just pay up and move on.

…noting that second-hand DDR4 RDIMM is typically much cheaper than ECC UDIMM.

ZFS Scrubs with no ECC (what could possibly go wrong?)

TrueNAS General

pmh January 14, 2025, 1:29pm 10

60f

9 Likes

TrueNAS Scale on Arm (2024 Thread)

Topic		Replies	Views
ZFS Pool Health marked Unhealthy TrueNAS General SCALE	13	1370	September 1, 2024
All disks in pool Degraded TrueNAS General	60	632	November 1, 2026
Checksum Error but SMART test is good? TrueNAS General SCALE , Hardware	20	454	April 30, 2025
ECC memory vs Non-ECC memory - Poll! TrueNAS General Hardware , ZFS	108	4650	March 18, 2026
First Build - Maybe Ryzen TrueNAS General Hardware	16	663	June 9, 2025

ZFS Scrubs with no ECC (what could possibly go wrong?)

Related topics