What is the 3-2-1-1-0 backup rule?

It is the modern extension of the 3-2-1 rule for the ransomware era. Keep three copies of your data, on two different media, with one copy offsite, plus one copy offline and zero errors on recovery. The two extra numbers exist because attackers now specifically target reachable backup infrastructure.

How is 3-2-1-1-0 different from the classic 3-2-1 rule?

The classic 3-2-1 rule assumes the threat model is failure and disaster. The 3-2-1-1-0 rule adds one offline copy and zero recovery errors to reflect that the current threat model is a determined attacker who targets backups first and encrypts the reachable copies. The offline copy is the one they cannot reach.

Does immutable cloud storage satisfy the offline 1 in 3-2-1-1-0?

No. Immutable cloud storage is still online. It is a logical control on a network that remains reachable and defended by identity. The offline 1 in the rule specifically calls for a copy that has no network path, which is what a physical air gap like Firevault Offline Secure Storage provides.

How does Firevault satisfy the offline 1 in the rule?

Firevault Offline Secure Storage is a physical air gap at Layer 1. The storage hardware has no network interface enabled while offline, so there is no IP, no listener and no credential path. Connection windows are scheduled, identity verified and logged on a separate management plane, giving you the offline 1 with a tamper evident audit trail.

How do I prove the zero on recovery to auditors and insurers?

Run scheduled test restores, log the outcome and keep the evidence. Firevault connection logs record every online window and its purpose, which combines with your backup platform's restore test log to prove end to end that the gold copy is verifiably restorable. That is what most cyber insurance renewals are now asking for.

Why OSS

The 3-2-1-1-0
Backup Rule

Three copies, two media, one offsite, one offline, zero recovery errors. The modern reading of the backup rule, and where a physical air gap sits inside it.

The five numbers

What Each Number Actually Requires

Plain definitions for each digit in the rule, and what a modern ransomware resistant estate needs to satisfy them.

Production plus two backups

3 copies of your data

Keep at least three copies of every important dataset. The live production copy counts as one. Two independent backup copies protect against the failure of any single storage system, and against the ransomware playbook that targets a single backup platform first.

Production is copy oneTwo independent backupsNo single storage dependency

Diverse failure and attack modes

2 different media

Spread the copies across at least two different storage media. Disk and object storage. Object and tape. Cloud and physically disconnected disk. Different media fail differently and are targeted differently, so a single class of failure or exploit cannot take every copy at once.

Diverse storage typesDiverse vendors and firmwareDiverse attack surfaces

Protection against site loss

1 copy offsite

At least one copy lives away from the primary site, whether that is another data centre, another region or a Firevault Bunker. Fire, flood and localised destructive attacks stop at the site boundary, and the offsite copy remains available to rebuild from.

Different site or regionIndependent power and networkSurvives physical disaster

The physical air gap Firevault provides

1 copy offline

One copy is offline and out of reach of the production network. This is the modern addition to the classic 3-2-1 rule and the one that ransomware operators cannot defeat remotely. Firevault Offline Secure Storage is designed specifically to be this copy, with Layer 1 disconnection and a tamper evident audit trail.

No network path when offlineOut of band switching onlyTamper evident connection log

Verified restores, not hopeful ones

0 errors on recovery

A backup that has never been restored is not a backup, it is a belief. The zero on the end of the rule requires regular, verified test restores that prove the copies are readable and consistent. A gold copy that cannot be restored on demand is worse than no plan at all.

Scheduled test restoresIntegrity verified end to endRunbooks proven, not written

Read the pillar guide, or continue with the comparison against immutable backup.

Physical air gap storage for ransomware protection Air gap vs immutable backup What is Offline Secure Storage