Backup strategy (3-2-1 rule)

In short: The 3-2-1 rule says: three copies of your data, on two different media, one of them at a different location.

In more detail: That way you survive disk failure, theft, fire and ransomware. A backup only counts once you have tested the restore. Synchronisation (for example a cloud folder) is not a backup, because deleted or encrypted files are synchronised too.

Our context: The document vault and the budget book store locally in the browser. Browsers can delete data, which is why there is a backup (ZIP or JSON) under “More”.

In Depth

• Full, incremental, differential backup: everything, only changes since the last backup, changes since the last full backup.
• Offline copy: A disconnected copy protects against Ransomware.
• Encrypt: Encrypt backups on external media or in the cloud.
• Retention: several generations, not only the last one.
• Test restore: Restore a file regularly.
• Recovery objectives: RPO (how much data loss is tolerable) and RTO (how long it may take).

See also: Ransomware, RAID