Live data from Hacker News

How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

neil.computer

71–80 of 265 posts

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#72
post #68
post #60

Earlier quoted context omitted.

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?

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]…

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...

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#73

I came to the same conclusion when I built my NAS. Just Nix for the system, zfs for raid and docker compose for any service I might want to run. https://www.splitbrain.org/blog/2025-08/03-diy_nas_on_nixos

I'm also using NixOS for my NAS, you should look into quadlets (docker containers managed by systemd) to manage containers with nix.

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#74
post #68
post #60

Earlier quoted context omitted.

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?

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]…

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.

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#75
I killed 2x 4tb Nvme drives on Pciexpress with ZFS raid1 under proxmox, got them replaced, tried again on both pci-express and usb adapter kept getting io problems there too with zfs, drive gets disconnected during scrub or high load, tried already kernel or power management options for pciexpress and usb without sucess, managed to reproduce with high load.

or proxmox ( especially community edition) is fucked or zfs is still unstable, surprisingly with different drives on different interfaces I obtained same results, didnt swap proxmox for clean os, that might being some changes since modules and options would be different i guess. ( drives firmware etc are fine and performing well when inspected with proprietary windows tools)

just search zfs nvme pcie or usb problema or disconnect and you see similar stability problem for different users in different cases (os, drives etc), but also unraid and others, maybe somewhere is rithe right combo of options/glitches but didnt find it yet

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#76

Earlier quoted context omitted.

I would kill (figuratively, anyway) to have no AI whatsoever. No slop machine threatening to replace my job, or turn my job into babysitting its stupidity, and hardware would be reasonably priced? That would be awesome. AI has brought me nothing but downside.

AI has freed most people I know from the tedious job of writing actual emails and birthday greetings - leaving then more time to e.g. wash dishes or clean the floor. Seriously, if arts and creativity is what sets humans apart from other animals, then AI has almost completely displaced our capacity to even consider doing these activities ourselves. People reach for AI when they should be composing a birthday greeting…

Is it a genuine birthday greeting if you just let AI do the job?

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#77
I really, do not want to have a big server rack lying around at my house. I have a couple of SSDs that are not being used and 3 USB HDD drives. I also have a PN50 that I am not using as well.

I am thinking of buying a USB bay with 5 SSD slots in it and then 3 HDD drive. My use case is very, very cold. It is mostly just readonly data with some rclone sync every week.

Does anyone have a suggestion? I am pretty much relying on ZFS to do all the redundancy for me.

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#78
post #68
post #60

Earlier quoted context omitted.

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?

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]…

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.

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#79
post #4
post #3

I still pay for snooty, and the reason for that is that when a disk goes bad (not if; when) I pop its tray out, replace the disk, pop the tray with the disk back in, click a couple of widgets, and that’s it. I know it will be rebuilt properly. (And I know I have to do that, because when the disk fails it beeps and lights a led near the bad disk) It’s easy to build a NAS such as the one described in this article, but…

Is snooty a autocorrect for Synology or some other product?

Indeed. Didn’t notice and it’s too late to edit now.

Re: How to Build a Minimal ZFS NAS Without Synology, QNAP, TrueNAS (2024)

#80
post #3

I still pay for snooty, and the reason for that is that when a disk goes bad (not if; when) I pop its tray out, replace the disk, pop the tray with the disk back in, click a couple of widgets, and that’s it. I know it will be rebuilt properly. (And I know I have to do that, because when the disk fails it beeps and lights a led near the bad disk) It’s easy to build a NAS such as the one described in this article, but…

That is kind of exactly how zfs works though. The guide isn't complete, sure, but "rebuilding" the array is just replace the disk and run a single zfs command.

That’s comforting to know; that wasn’t true in the past for ext4 over lvm (is it true now?).

But what is that command? And how do you know which disk has gone bad?

I am sure I can get an answer from Google / Claude / ChatGPT, but a guide is incomplete without it - and the failure report should be active like a beep or flashing hardware light - I typically log into my NAS only a few times a year. A motd or other banner isn’t sufficient.

Post reply on HN