Anecdote: I once lost a lot of files over a period of ~two years on a desktop PC running ZFS with bad non-ECC RAM. I figured out what was going on after a bunch of audible corrupt blips kept appearing in all my favorite FLAC rips as they got mapped into the bad memory, checksummed against the contents still on disk, and written back "corrected" as far as ZFS was concerned. There's a better (i.e. not by me) write-up of it in the OP of this thread under "What happens when non-ECC RAM goes bad in a ZFS system?": https://www.truenas.com/community/threads/ecc-vs-non-ecc-ram...