What is 3-2-1-1-0 Backup Rule?
Do not keep the original and every spare key in the same room. Keep several usable copies, place at least one elsewhere, protect one from being changed, and regularly prove that the key still opens the door.
The Technical Explanation
The 3-2-1-1-0 approach means keeping multiple copies of data, using different storage types, maintaining an offsite copy, keeping one offline or immutable copy, and achieving zero unverified backup errors.
Business Impact
It is a design principle, not a guarantee. It aims to achieve zero unverified backup errors through regular checking and restore testing.
Warning Signs
- Backup is always connected to the production server
- One administrator can delete every copy
- All copies are in the same office
- No restore has been tested
- Backup warnings are ignored
Practical Solution
1. Inventory critical data and applications 2. Create independent local and offsite copies 3. Add offline or immutable protection 4. Secure backup administration separately 5. Monitor every job and capacity alert 6. Test recovery against RTO and RPO
Frequently Asked Questions
Does cloud backup automatically mean immutable?
No. Immutability depends on the service, configuration, permissions and retention controls.
How often should restore tests be done?
Frequency should reflect criticality and change; critical systems need more regular tests than low-impact archives.
Can a USB drive be an air gap?
A disconnected drive can provide physical isolation, but handling, encryption, rotation and testing must be controlled.