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

neil.computer

241–250 of 265 posts

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

#241
post #158

Earlier quoted context omitted.

What do you dislike about SATA?

The cables and how they have to be managed/positioned in a case. I've had panics over a drive failing when it was just the cable after I'd already replaced the drive, restored data, and ran tests on the old drive that turned out to be fine each time.

I have multiple home servers running ZFS and the first thing to check when encountering errors is the SATA cables. Those blue foil fan-out types are the worst from my experience.

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

#242

Earlier quoted context omitted.

> The odds of this happening go way up the larger your individual drives are. This is a common claim, but honestly, citation needed. We can't just apply bit error rates from the datasheet that haven't been updated in 15 years. I'm sure a 2-day rebuild is a little more risky than a 4-hour rebuild, but I'm not convinced it's by all that much. Especially if you had a monthly scrub going to prevent disk rot and disks sec…

>> The odds of this happening go way up the larger your individual drives are. > This is a common claim, but honestly, citation needed. FWIW, here's the quick & dirty argument for that: Assume: - We're working within a given generation of disk technology, with comparable drive and interface tech. - The drives' I/O speed is relatively constant, not scaling with the drive capacity. - The chance of any given bit (of dat…

> - The chance of any given bit (of data on a disk) going bad, in a given time interval, is relatively constant.

We can't just assume this, though. Especially for data that's being checked regularly, because the drive can see how many pre-ECC bits have gone bad and rewrite iffy sectors.

And even if it's true, it's normal to go years without errors. If you have a 15% chance of getting an error each year, and your degraded array has 4 drives without redundancy, then the chance of getting an error in 4 hours is .02% and your chance of getting an error in 48 hours is .3%. Having that risk show up once every few years is pretty negligible compared to everything else that could go wrong with your array.

On top of that, if you don't have a hot spare and it takes 5 days to get a new drive, the difference in resilvering speeds is now 5.2 days versus 7 days and that barely matters.

The main situation where you have to worry about extra drives failing is when you think the resilvering process will greatly accelerate drive deaths. And that depends very much on the specific numbers you have in mind.

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

#243
post #231

Earlier quoted context omitted.

> AMD has been allowing ECC on lots of regular hardware for a long time. Often unsupported or untested by the motherboard manufacturer, because the precedent set quite a while ago has stood so strongly. > because it costs significantly more [...] and the performance specs are poor Because it's niche. If a large share of the desktop market was using ECC memory, the extra cost would have been 10-12%, and a typical kit…

> the precedent set quite a while ago has stood so strongly. I wasn't really around for it, but I appreciate the early penny pinchers that developed fake parity ram. The IBM PC required a parity bit per byte?, but you could add an xor chip to calculate it at read and save out on the expensive ram chip. I wouldn't mind paying a little more for ECC, what with the extra chip and a little more circuitry, but desktop ECC…

My favorite parity trick was how the N64 was designed around ECC RAM chips but didn't bother using ECC, so it has a ninth bit at every address that the CPU ignores and the GPU uses as extra storage.

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

#244
post #104

Earlier quoted context omitted.

I have external parity for everything with rsync. I don't have any storage that isn't matched with external backups. Fortunately I've never seen any bitrot or had a drive fail on me since I tend to replace them before they do. And yeah, I could add in some extra HDDs for RAID, but this is more a personal choice because of how much I hate SATA. Filesystems like ext4 are because I value boring and rock solid stability…

What do you use for external parity? Par2? If you were to replace your current drive with a new larger one and your RAM or your SATA controller silently corrupted the files how would things play out? Would these corrupted files propegate to the backups? Ext4 is battle tested so I understand your reasoning. I think you just need to figure out a way to detect silent corruption and a way to snapshot your files in case t…

+100 to this. I don’t want to be overtly paranoid but you genuinely are unlikely to notice real data corruption unless you actually checksum.

It is a matter of time when you’re storing a lot of data — not if.

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

#245

Earlier quoted context omitted.

You can do those things with LVM snapshots too, that's what they are used for.

When we allocate space to an LVM snapshot, the COW data is written to that space and then when that space is used up the LVM snapshot must either be given more space or must be deleted. When a ZFS snapshot is marked, then changes to existing blocks in the snapshot as well as new writes all go to free space in the disk. There is no pre-allocated space within which these COW changes are written to. Thus, we could have…

That would be a thinly-provisioned snapshot in LVM.

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

#246
post #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.

But why? Why not the standard oci-containers module?

I've seen the quadlet-nix project but don't get what additional it gets me.

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

#247
post #7

Not a great time price-wise to be building a NAS, but I have been doing so for the last two weeks. Inside a Jonsbo N6 case, which is pretty nice with an 8x SATA backplane and drive bays (unlike the earlier Jonsbo variants). I ended up on shucking 4x the 14 TB WD Elements Desktop. They contain helium drives, the WD140EDGZ in my case, and are about a third cheaper than 4x the 12 TB WD Red Plus drives (which are air-fil…

> Not a great time price-wise to be building a NAS That under-states the matter. It is a terrible time, price-wise, to build a NAS. I'd almost rather have no AI whatsoever and have storage 1/10 the price of pre-AI times. (If there were a magical choice between having AI and significantly more expensive storage, and having no AI and some program to dump that investment money into getting and somehow leveraging signifi…

Looking at current hd prices, I keep kicking myself for giving away several 3tb and couple of 4tb drives I had in my unraid server few years ago when I started upgrading my array to 8 and 12tb drives. At the time, a drive slot in my server was more valuable to me than a mere 3tb drive. i could have kept them for emergencies if any one of my array drives fail.

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

#248
post #57

Earlier quoted context omitted.

smartmontools makes this trivial and can email you which might be better than beeping and lights if you’re not always near your server. I use that plus smartctl_exporter so I can do metrics and alerting off that.

smartmontools misses data corruption at the drive layer, as it trusts the drives to report faithfully. "In hashes I trust"

Yeah, for that I use periodic scrubs and zfs event daemon

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

#249

Earlier quoted context omitted.

I'm doing it anyway and I've found some secondhand deals. Maybe COVID homelabbers are offloading gear? I built a 24 TB HDD NAS in a 36 bay chassis for around $1000 all-in: mb, ram, rails, chassis, rack, disks, hba, nic Awful Watts/TB but the plan is to run it and the GPU rig on solar.

36 bays and only 24T of storage? Can't you get that in a single disk that costs less than a kilodollar?

That will be a single point of failure, though. (Which you might not care about depending on the backup strategy.)

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

#250
post #191

If you use LVM you can have a similar pool of storage with 1GB RAM or even less, instead 8GB (ZFS requirement). Caveat: LVM does not have built-in snapshots like ZFS has.

Where does that 8GB requirement come from?

From the official documentation.
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