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Plain Copies with Rsync

Scope: the simplest backup of all — copying files with rsync — and an honest account of when it's enough and when it quietly isn't.

The tool

rsync copies files from A to B, transferring only what changed. It's on every Linux and macOS system (Windows via WSL or cwRsync). A backup-flavored invocation:

rsync -avh --dry-run ~/Documents/ /mnt/backup-drive/Documents-copy/

sending incremental file list
created directory /mnt/backup-drive/Documents-copy
./
newfile.txt
photo.bin
report.txt
notes/
notes/todo.txt

--dry-run lists what would happen and changes nothing — run every new rsync command this way first. Drop it when the list looks right. (Note the trailing slashes: ~/Documents/ copies the contents; without the slash it copies the folder itself into the target. Everyone learns this once, the loud way.)

When a plain copy is the right answer

  • The second drive in a 3-2-1 setup, where a different tool (restic/Borg) provides the versioned copy.
  • Huge media files that don't change and don't dedupe — copying is copying.
  • A bootable-ish clone you want to browse with ordinary file tools, no restore step. This is rsync's genuine advantage: the "backup" is just files, readable by anything, forever, with no restic/Borg installed.

When it quietly isn't

Read the failure list against What a backup is:

  • No history by itself. Tonight's copy overwrites last night's. The file you corrupted on Tuesday is corrupted in the copy by Wednesday — rsync's job is to make B match A, including A's mistakes. (Flags like --backup --backup-dir= can keep replaced files aside, at which point you're hand-building what restic gives you for free.)
  • Deletes are contagious. Add --delete (needed to keep a true mirror) and deleting a file deletes the copy. Leave it off and the copy grows stale extras. Neither is versioning.
  • No encryption, no integrity checking. Files sit in the open, and a silently corrupted copy is discovered on restore day. (--checksum verifies during transfer; it doesn't audit the copy later.)
  • Databases and open files have the same mid-write trap described in What to back up.

The verdict

rsync is a superb copying tool and a partial backup. If your whole strategy is "rsync to an external drive," you have protection against a dead disk — the most dramatic failure — and weak protection against the most common ones (your own deletions and mistakes). Pair it with one versioned copy, or graduate the important folders to restic, and the combination is genuinely solid.