Not the parent, but I use a similar setup. I avoid this be keeping my 2nd drive formatted as btrfs, primary is xfs. After I rsync to the btrfs drive, I take a s

Not the parent, but I use a similar setup. I avoid this be keeping my 2nd drive formatted as btrfs, primary is xfs. After I rsync to the btrfs drive, I take a snapshot. I only rsync every week, my data doesn't change often and if it does, I can trigger a manual rsync using the same script in my /etc/cron.weekly/ edit: I do use borg to backup to my cloud storage server, since it's encrypted. Time4vps has super cheap storage servers, 1TB for about $20 a quarter. (my affiliate if anyone is interested; https://billing.time4vps.eu/?affid=1881 https://billing.time4vps.eu/?affid=1881)