Everyone has a data-loss story: the dead laptop before a deadline, the phone in the lake, the ransomware email. The fix has been known for decades and takes an afternoon to set up: the 3-2-1 rule.
The rule
- 3 copies of anything you care about — the original plus two backups.
- 2 different media — e.g. your computer plus an external drive, so one hardware failure can't take both.
- 1 copy offsite — cloud storage or a drive at another location, so fire, theft or flood can't take everything.
Every horror story maps to a missing leg. Laptop + external drive in the same bag, bag stolen: had 2 copies, 2 media, zero offsite.
What to back up (and what to skip)
Prioritise the irreplaceable: documents, photos, tax and legal records, project files, password-manager exports. Skip what's re-downloadable: applications, movies, the OS itself. A focused 50 GB backup you maintain beats a 2 TB mirror you abandon.
Compress PDFs and images before backup — same documents, a fraction of the space.
Open Compress PDFMaking it automatic
- Cloud sync for the working set. Keep active documents in a synced folder — that's your offsite copy, updated continuously.
- External drive on a schedule. Weekly for most people; put a recurring reminder on it, because manual backups stop the month you get busy.
- Yearly archive. Once a year, burn the truly permanent stuff (tax records, photo library) to a drive that then lives at a relative's house or in a drawer at work.
The step everyone skips: test the restore
A backup you've never restored from is a hope, not a backup. Twice a year, pick a random file and actually recover it from each backup location. You're testing three things: the copy exists, it opens, and you remember how.
Privacy while backing up
Sensitive documents deserve care in transit and storage: strip PDF metadata before archiving shared copies, protect confidential archives with a strong passphrase, and prefer tools that process files locally so preparing the backup doesn't itself leak the data.