tl;dr: A proper backup strategy quickly balloons in complexity: you need snapshots (not mirrors) to survive ransomware and mistakes, GFS rotation to manage storage growth, deduplication via hard links to save space and bandwidth, database dumps to avoid corruption, and 3-2-1 distribution across media and locations. Cloud object storage adds further wrinkles like metadata loss and per-file costs that push you toward chunked tarballs. The author's conclusion: don't roll your own—use Borg or Restic, and actually test your restores.