Secure backups that survive device loss

The backup has to be usable

A backup is not a pile of files. It is a tested ability to restore the right data after a lost device, failed disk, ransomware event, account lockout or accidental deletion. Start by listing the data that would be difficult or impossible to recreate: photographs, identity records, recovery codes, source files, documents and configuration.

Use more than one copy

Keep multiple copies in different failure domains. A practical pattern is a working copy, a local backup, and an offline or separately authenticated copy. A second disk next to the computer is useful against drive failure but not against theft, fire or ransomware that can reach mounted backups.

Backups should be versioned when possible. If corruption or encryption is discovered late, the latest copy may already contain the problem. Keep at least one copy that is not continuously connected or writable by the everyday account.

Encrypt and practise recovery

Encrypt portable and cloud backups, but document how the key is recovered. A backup encrypted with a key that exists only on the lost device is not a recovery plan. Store recovery material separately and protect it against unauthorised access. Test restoration on a spare device or temporary directory; a backup that has never been restored is an assumption.

What to record

Record the backup locations, schedule, retention period, encryption method, recovery owner and last successful restore. Keep the record short and avoid putting secret keys in the same document.