Cheapest and power efficient TrueNAS build with ECC

TrueNAS General
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Hey guys, I’m very new to TrueNAS and its hardware requirements. I’ve read a bit on the topic of ECC and ZFS for a NAS. For 2025, what would be the most cost-effective and power-efficient build just for a NAS? I’m going to use Proxmox, Docker, and Plex on other machines. In light of this, how much RAM will I need for a NAS? ECC RAM is very expensive, so I don’t want more than what is necessary for now and the next 5 years.

With all the files stored on TrueNAS, I want to use other PCs, whether it’s Plex or Docker, to access the data from there so that I can install the smallest SSD for those machines.

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Cost effective, power efficient, ECC. Choose any two !

ECC doesnt have to be expensive, if you choose DDR4 RDIMM.

Power efficient with ECC: Intel Atom C3000 (RDIMM) series, Intel Xeon-D ( RDIMM) or Xeon E (UDIMM).

Ryzen/EPYC 4004 also with UDIMM, but alot less choice in boards.

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Try to get a used Supermicro Mini-ITX board, A2SDi oder X10SDV series. If you have that starting point you can build from there.

Both platforms are super solid for a NAS.

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Rough guidance: 1 GB RAM per 1 TB storage… relaxing when you get past 32 GB.
As said, second-hand DDR4 RDIMM is cheap.

How much storage do you need?

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Is there such a thing as an ECC UDIMM?

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Of course.

https://geizhals.de/samsung-dimm-16gb-m391a2k43bb1-cpb-a1354980.html

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Isn’t the Intel Atom using very old and slow CPUs?

If I want to buy a new one, which Ryzen CPU is low power and supports ECC? Which motherboard do I get that will support ECC?

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Atom is a processor family that gets refreshed all the time. I think the most recent generation is the X7000 series starting from Q2 2024.

I think all Ryzen CPU’s (unofficially) supports ECC, the bigger question is which motherboard does. Off the top of my head, ASRock Rack series is one such family of motherboards that supports it.

Personally, I like to go with Intel because I’m not a big fan of unofficial support plus used DDR4 RDIMM is cheap and I like having 200+ GB of RAM without paying an arm and a leg.

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Most (but not all!) desktop Ryzen CPUs unoffcially support ECC, but are not quit low power at idle due to the I/O die; the exceptions are some processors which are actually APUs with a disabled/defective iGPU.
Ryzen APUs have low idle power (their monolithic die is optimised for that, as they are meant for mobile) BUT then only the PRO versions support ECC.

On the motherboard side, your best bet is a server motherboard from AsRock Rack (X470/X570/B550/B650D4U), or Gigabyte (MC12-LE0, MC13-LE0/LE1), or Supermicro workstation motherboard H13SAE-MF.
For certified ECC support, take a B650D4U, MC13-LE# or H13SAE-MF and pair that AM5 motherboard with an EPYC4000 CPU.

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What about RAM? What’s a good value ECC RAM?

I only see AMD EPYC 4005 and nothing on the EPYC 4000. I want to buy only new, and it seems like the cheapest AMD entry CPU is US$240.

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There’s EPYC 4xx4 (Zen 4) and 4xx5 (Zen 5); “4000” is shorthand for both, but there’s no part with this exact number.

$240 looks like MRSP for EPYC 4245P, and quite wallet-friendly for an ECC-certified part. “Cheapest” and “buying new” do not go well together but you may look for a 4124P.

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When it comes to building a NAS, the “right” setup really depends on what you actually plan to run on it. Are you just using it for storage/archiving and backups, or are you planning to run VMs, heavy plugins, or services directly on the NAS? That will strongly influence CPU, RAM, and ECC requirements.

For a cost-effective and power-efficient build, one interesting option is to look at older desktop/workstation Xeons, like the E3 series, especially v5 (Skylake). These CPUs officially support ECC (UDIMM), offer up to 4 cores / 8 threads, and are based on the same architecture as Core i7s. Their TDP and idle power usage is quite reasonable, making them a solid choice for a low-power NAS.
With luck, you can get such CPU for around 20 EUR…

The tricky part is finding a compatible motherboard—look for C236 chipset boards for proper ECC support. These aren’t super common, but they do exist.

A practical and cost-efficient example: an HP Z240 workstation with an E3-1245 v5. Roughly comparable to an i7-6700 with integrated GPU, so you save power if you don’t need a separate graphics card. Ideally, you’d want ECC RAM already installed, though in practice that can be rare.

Downsides of the HP Z240: the PSU and some parts may be proprietary, but there are usually workarounds if you’re handy with hardware.

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Thank you, my friend. I meant the cheapest new part I can get. Really appreciate your help.

What about RAM? What is a reputable brand and where should I get it to pair with an EPYC CPU?

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I only intend to use this as a NAS and I’ll be using another machine for VMs and containers. My main purpose will be for storage, archive, and backup. Data integrity and resistance to bitrot are top priorities. I’m not familiar with server parts and ECC RAM.

I got priceless family photos and videos that I want to save. I care enough that I’ll spend the extra money on ECC RAM and hopefully with ZFS, it’ll give me the best chance to preserve the data.

How do I best set up TrueNAS to accomplish this goal? What is the minimum number of HDDs to ensure there is enough parity data to fix any potential data corruption?

Once I finish building the NAS, can I shut it down when it’s not in use or it should be best kept running 24/7/365?

What other hardware do you think I’ll need?

Thank you!

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NAS basically just means “Network Attached Storage” and doesn’t really tell you much about the intended use.

Since your main purpose is to use it as an archive for priceless data, I would lean towards RAIDZ2 or even RAIDZ3, or alternatively a 2-way or 3-way mirror. Personally, I prefer the RAID-Z configurations because they usually offer more usable capacity, and I/O performance is secondary for this kind of use.

I’m in a very similar scenario: I want to store important and irreplaceable data as safely as possible. I do this with TrueNAS Core, using a 6-wide RAIDZ2. The drives are used Enterprise HDDs (HGST 6TB SAS),connected via an HBA in IT mode. For my purposes, these drives should still have plenty of life left, and I bought them about two years ago for roughly €45 each (~€7/TB at the time, which I thought was pretty reasonable).

ECC RAM is a real point of debate in the community, but I personally didn’t want to risk a few euros’ worth, so I went with a Xeon CPU and ECC RAM. This should give me some protection against bit flips, bit rot, and issues during scrubs.

Looking forward, I also need to think about other risks:
my own mistakes (accidentally destroying a pool, deleting data)
and other disasters like fire, lightning, water damage, or theft.
No amount of RAID-Z3 will protect you against thoss (remember:“RAID is not a backup”).
So I’ll need a practical off-site backup strategy as well.

24/7/365…this is also one of those topics where opinions differ… For me, I only fire up the NAS when I actually need it—running it 24/7 would be overkill.
If, in your scenario, you actually use the NAS several times a day, then keeping it running continuously would be worth considering.
If you end up running it continuously, you might also want to consider a UPS, since a sudden power outage can cause serious problems.

But let’s be honest… all in all, the term “power-efficient” slowly starts to take on a different meaning …
(Although it’s still definitely better compared to a large enterprise server that consumes 1000 watts or more.)

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I tend to assume that ECC RAMis well standardised and generally better quality than average. For extra peace of mind, go directly for first-party manufacturers: Micron, Samsung, SK Hynix.

Mirrors: 2
Raidz1: 3
Raidz2: 4
copies=2: 1!
Add at least one drive (and possibly a few more) for a backup elsewhere to keep your data safe. ZFS can have hiccups. Burglars break in. Houses burn or get flooded. Sh!t happens.

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:face_with_symbols_over_mouth:

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RAID is not a backup. A NAS with RAID can be a part of a good 3-2-1 backup strategy. But if you have irreplaceable data, dont rely on a single system to keep it safe. Doesnt matter if that system uses ZFS or not, ECC or not.

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…which is where a 4-wide raidz2 and a lone drive as external backup is A LOT better than just a single 5-wide raidz3 in the NAS. Even if the lone backup drive is not ZFS, is ZFS without redundancy, or uses copies=2 for protection against bit-rot (but not against drive failure obviously).

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Yessir, thanks for the reminder. I still want to have a properly configured NAS as part of the process.