Knowledge base · practical guide
The 3-2-1 backup rule, explained simply
A reliable backup does not have to be complicated. The 3-2-1 rule reduces the risk of losing important files after hardware failure, theft, fire or ransomware.
The rule at a glance
- Keep three copies of your data: the original and two backups.
- Use two different kinds of storage, such as a computer, an external drive and cloud storage.
- Keep at least one copy somewhere else, often in a cloud account.
Why keep more than one copy?
- A failed drive does not take every copy with it.
- A copy stored elsewhere can still be available after theft or fire.
- A disconnected backup is harder for ransomware on the computer to reach.
A practical starting point
- Use an external drive and a separate cloud backup for important files.
- Set backups to run regularly and check that the files can actually be restored.
- Keep the external drive disconnected when the backup is complete, if your workflow allows it.