After the years what ended working confortably for me is some
machine with netbsd serving a ffsv2 (logged) partition through nfs,
and using rsync for incremental (--link-dest) and full backups. No
RAID, no zfs, just an rpi4 with usb3 disks. If you are going to
try overtake netflix, no, this setup will not work, but for what
I read, I think this would work ok for your needs. After doing some
work I run a script to make the backing up, one of the full backups
to an encrypted disk (cgd) I can take with me. I like to do this
with an rpi4 because it takes little space, usb3 disk are ok for
me and I can plug them rapidly to another machine, but again, it
all depends on what are your needs. One little advise, think about
what are your _real_ needs before building your setup, don't
overcomplicate your life.
Regards.
adr