ZFS (mirrored) two HDDs. If one HDD fails, then replace it and let it rebuild. Use 3 HDDs mirrored if you really think you could get a failure while the array is rebuilding.
Also have two external backups, one you do regularly at home, and another you keep off-site. When you visit that location (be it your parents, siblings, relatives, friends house) swap out your external backup with their off-site to ensure its kept up to date.
Make sure all disks are fully encrypted of course.
ZFS (mirrored) two HDDs. If one HDD fails, then replace it and let it rebuild. Use 3 HDDs mirrored if you really think you could get a failure while the array is rebuilding.
Also have two external backups, one you do regularly at home, and another you keep off-site. When you visit that location (be it your parents, siblings, relatives, friends house) swap out your external backup with their off-site to ensure its kept up to date.
Make sure all disks are fully encrypted of course.