Wild shot here, but are you sure your disks are healthy? They might have errors that could throw off truenas

I see, thanks for clearing that up. In my situation, keeping a few terabytes on 3 hard drives and backing up to a reliable cloud copy (not sync, as you mentioned) is good enough for me. Optical media is impractical with the amount of data, and tape drives far too expensive for just a few TBs.

Whatever you decide to do, please implement 3-2-1 backups (3 backups: 2 backups offline, 1 offsite). This will cost more obviously, but family data is important and its safety shouldn’t be skimped on.

They’ll never encrypt my 2000 DVDs!