Backups: The Only Thing You Cannot Do in Advance

Three copies of your data, on two different kinds of media, one of which is somewhere else. It is unglamorous and it works against every realistic threat at once — accidental deletion, device failure, theft, ransomware, and the fire.

• Three copies: the original plus two backups.
• Two media types: a drive and a cloud service are genuinely different failure modes.
• One offsite: fire, flood and theft do not respect your filing cabinet.

This distinction matters more than anything else on this page. Syncing propagates changes — including deletions, and including ones made by malware or by you at 2am. A synced folder mirrors whatever happened, including the disaster. A backup keeps previous versions, which is the entire point.

• If you deleted it and it is gone from every device, you were syncing, not backing up.
• Look for version history specifically. That is the feature that makes a cloud service a backup.
• Photos deserve special attention: deleting a photo from a synced phone can delete it everywhere, and it is a leading cause of permanent family-photo loss.

• Accidental deletion — by far the most common, and the easiest to survive with version history.
• Device failure — phones and laptops die, usually without warning.
• Ransomware — encrypts your files and demands payment, often via a synced folder.
• Theft and fire — the reason for the offsite copy.
• The quiet one: a failing drive that has already started losing data without telling you.

• Restore a few files to a different device or location. If you cannot restore, you do not have a backup.
• Check that the backup is running. Backups fail silently, and a failed one looks identical to a successful one until you need it.
• Confirm the schedule is one you would actually keep — a daily backup you switch off in week two is worse than a weekly one you keep.
• Test a full restore once a year with a laptop you do not mind losing.