How do I back up my files?
A backup that would actually survive the things that destroy data — and the test that proves it works.
- Difficulty
- beginner
- Time
- 1 hr
- Read
- 2 min
Short answer
Three copies, on two different types of media, with one off-site. In practice: the files on your computer, an automatic backup to an external drive, and a cloud copy. Then restore a single file to prove it works — an untested backup is a guess.
Most people's backup is one external drive kept next to the computer. That protects against drive failure and nothing else — not theft, not fire, not ransomware, not accidental deletion that syncs everywhere. The 3-2-1 rule exists because all of those happen.
What you'll need
- External drive at least twice your data size
- Cloud backup subscription (optional)
Step by step
- Identify what you would actually miss.Documents, photos, anything you have made. Applications and the operating system can be reinstalled.
- Set up automatic local backup to an external drive.Time Machine on macOS, File History or a backup tool on Windows. Automatic, because manual backups stop happening within weeks.
- Add a cloud copy for anything irreplaceable.This is the off-site copy. It is what protects against theft, fire and flood, which a drive on the same desk does not.
- Understand that cloud sync is not backup.Dropbox, OneDrive and Google Drive mirror your mistakes — delete a file and it deletes everywhere. Version history helps but it is a different thing.
- Keep at least one copy versioned or disconnected.Ransomware encrypts connected drives too. Versioned cloud backup or a rotated offline drive protects against it.
- Buy a drive at least twice the size of your data.Backup systems keep version history, which needs room. Too small a drive truncates the history.
- Test it: restore a single file and confirm it opens.The only way to know it works. Plenty of backups turn out to be empty, corrupt or missing the important folder.
- Check the backup is still running every few months.Backups fail silently. A calendar reminder is the only reliable way to notice.
Tips
- Two external drives rotated, one kept elsewhere, is a cheap off-site strategy with no subscription.
- Label drives with what is on them and when they were last used. Unlabelled backup drives get wiped by accident.
- For photos specifically, cloud plus a local drive covers most realistic failure modes.
Common mistakes
- One drive kept beside the computer — It protects against drive failure only. Theft, fire and flood take both at once.
- Treating cloud sync as backup — Sync propagates deletions and corruption. It mirrors your mistakes rather than protecting against them.
- Never testing a restore — An untested backup is an assumption, and assumptions fail at exactly the wrong moment.
Questions people ask
What is the 3-2-1 backup rule?
Three copies of your data, on two different types of media, with one kept off-site. It is a rule of thumb that survives most realistic disasters — drive failure, theft, fire and ransomware.
Is cloud storage enough on its own?
It covers the off-site requirement well, but a local copy restores far faster and does not depend on an account you could lose access to. Both is the right answer.