I'm planning to build my own NAS and now decide to use Unraid instead of TrueNAS because ECC memory will be important to ZFS compared to other filesystems. (I saw this from a lot of discussions)
My question is why? I know ZFS rely on RAM for caching, but why ZFS is more vulnerable to memory corruptions? And why other systems like unraid and btrfs are not as emphasize ECC memory?
It's quite interesting to see two major voices. People from TrueNAS side suggest you must have ECC memory if you care about your data. But people from unraid side said ECC it's not worth the money.
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I also think if I keep a list of hashes when I back up my data, then ECC might not be nessary at all.
@skyblond ZFS manages the storage medium and use of it. If there is a corruption, it could destroy data on a drive or not recognize it.
I think it would be worth the compromise to use ECC. It could work without ECC ram but in a NAS I assume the Error rate would be higher. The uptime would see more potential errors from the time alone, not to mention the heat and other factors.
Nothing is ever a problem until it becomes problematic.
@AmpBenzScientist Thanks for the answer! ECC, to me, feels more like an insurance. Generally you don't need it, but when you do, you will be glad to have one. With my old NAS, I do have DDR3 ECC RAM, which is fairly cheap nowadays.
(BTW my old nas has dual E5 2695v3, which I can't run it 7x24 because it will literally blow up the electric bill and the single core performance is not that good)
However, for my new NAS, I decide to go with DDR5 and DDR5 ECC requires at least workstation hardware... And it's not cheap (not to mention that I'm in China and brands like ASUS don't sell workstation motherboard to individual consumers). So I guess for now I'll stick with non-ECC and do my best with backups.
@skyblond ECC is generally recommended in a RAID setup because it (usually) prevents corrupt data to be written to the disk. Regardless of the filesystem.
Think of ECC like disc brakes. You don't need disc brakes on a slow moving vehicle. Similarly, on a machines that handles a lot of data, you want ECC RAM to prevent data corruption.
If you maintain hashes of file written, you can get by with any setup. Make sure you have 3 copies of hashes and hash of the file containing hash itself.
@thefossguy Thanks for the answer! I think I'll stick with consumer hardware without ECC to bring the overall cost down. But I do plan to have backups following the 321 rule, along with hashes to ensure the backup is not corrupted silently.
The reason I don't want ECC is the cost. I have already blown up my budget with ASUS TUF Gaming motherboard and brand new intel 13th gen i5 because I don't want to gamble on cheap stuff.
I do plan on using those cheap stuff until I saw the comment saying it's frustrating when you have to going back and forth with the customer support team.