Term · Security & infrastructure
Backup
A backup is a copy of data — and, where needed, of system configuration — kept so that it can be restored after hardware failure, human error, software bugs or attacks such as ransomware.
[ 01 ]
Explained
What to back up
- Databases: customers, orders, content, users.
- Uploaded files and documents.
- Code and server configuration.
- Access to secrets needed to rebuild systems, stored securely.
The 3-2-1 rule
At least three copies of data, on two different types of storage, with one copy off-site. Modern practice adds an immutable or offline copy that attackers with stolen credentials cannot delete. See backup strategy.
Recovery objectives
- RPO (recovery point objective): how much data you can afford to lose, measured in time — it determines backup frequency.
- RTO (recovery time objective): how long systems can be down — it determines how recovery is organised.
Testing restores
A backup is only proven when it has been restored successfully. Test restores regularly in a separate environment and document the procedure.
After an attack
Restoring the latest backup is not enough if the vulnerability remains, or if the backup already contains malicious code. Identify the entry point first. See website hacked: what to do.
[ 02 ]
FAQ
Frequently asked questions
Is the hosting provider's backup enough?
It is a useful layer; an independent copy with a different provider or account protects against wider failures.
How long should backups be kept?
Long enough to recover from problems noticed late, within legal and data protection limits.