I replaced the RAM in my storage machine because of this earlier this year too. ZFS was reporting all sorts of errors, yet drive tests were showing no issues.

I replaced the RAM in my storage machine because of this earlier this year too. ZFS was reporting all sorts of errors, yet drive tests were showing no issues. I bought about 3 new drives before I realised what the root cause was. A real PITA. Next time I do a hardware refresh, ECC is definitely on the menu.