My personal files are ultimately a lot more important to me and much more irreplaceable than any files at work.
I'd never run a NAS without ZFS and ECC.
Both of which are 3-2-1 backed up.
Adding an ECC motherboard to my NAS would cost more than a quarter century of cloud storage for that amount of data.
The rest of my terabytes of data would be inconvenient to lose, but not fatal. In the worst case I'd need to track down a few rare DVDs and re-rip them.
Keep in mind that backups are a solution to a different problem than ECC.
If a file is silently corrupted you could be backing up the corrupt file for years and by the time you discover the problem, it has spread to every available backup.
a) 99%+ (or something) of the servers had zero reported errors for their lifetime. Memory usually works, no problems experienced.
b) Some of the servers reported one error, one time, and then all was well for the rest of their life. If this happens without ECC, and you're lucky, it's in some memory that doesn't really matter and it's no big deal. Or maybe it crashes your kernel because it's in the right spot (flip a bit in a pointer/return address and it's easy to crash). Or maybe it managed to flip a bit in a pending write and your file is stored wrong and the zfs checksum is calculated on the wrong data. If you're really unlucky, you could probably write bad metadata and have a real hard time mounting the filesystem later?
c) some servers reported the same address with a correctable error once a day; probably one bit stuck, any time data transits that address, that bit is still stuck, and that will likely cause trouble. If it's used for kernel memory, you'll probably end up crashing sooner or later.
d) some servers had a lot more ram errors; sometimes a slow ramp to a hundred a day, once or twice a rapid ramp to so many that the system spent most of its time handling machine check exceptions, but did manage to stay online but developed a queue it could never process. Once you're at these levels, you'll probably get crashes, but you might write some bad data first.
Ram testing helps on systems without ECC, but you won't really know if/when the ram has gone from working 100% to working almost 100%. I have a desktop that was running fine for a while, tests fine, but crashes in ways that have to be bad ram, and removing one stick seems to have fixed it.
If it would hugely impact your life if a bit were flipped from a 0 to 1 in your stored data - say you make videos or store your bitcoin wallet key on your NAS - you are running a risk not using ECC.
You may not have had issues or ever have issues with non-ECC. Your car may never be stolen if you leave the keys in either, but it's not a good risk proposition for most people.
