[AlexandrB]

Data that's about to be written to disk often resides in ram for some period of time - bit flips in non-ECC ram can silently corrupt the data before writing it out. ZFS doesn't prevent this though it might detect it with checksumming.

https://jrs-s.net/2015/02/03/will-zfs-and-non-ecc-ram-kill-y...