I do something like this with ZFS snapshots and syncoid. It runs every 15 minutes and sends the diff from the latest snapshot onto a second ZFS pool made out of

I do something like this with ZFS snapshots and syncoid. It runs every 15 minutes and sends the diff from the latest snapshot onto a second ZFS pool made out of a single HDD (and then updates that snapshot and discards deleted data). Works fine for about a year now.