The 3-2-1 backup rule: the simplest shield against ransomware

Ransomware encrypts an organization’s files and demands a ransom to restore them. No security tool is 100 percent effective; what saves a business on the day of an incident is a healthy, restorable backup.

What is the 3-2-1 rule?

• 3 copies of your data: the original and two backups.
• 2 different types of media: for example network storage (NAS) and tape or a separate disk.
• 1 copy off-site: in another building or a separate data center.

Many specialists now extend the rule to 3-2-1-1-0: one offline or immutable copy that ransomware cannot reach, and zero errors in restore tests.

Practical tips

• Keep the backup software’s accounts separate from the main domain and turn on two-factor authentication.
• Test restores regularly; a backup whose restore has never been tested is only a hope.
• Define the acceptable downtime (RTO) and acceptable data loss (RPO) for each service, and plan your backups around them.