Backup strategy

RAID is not a backup: how to protect data with the 3-2-1-1-0 rule

RAID (whether 1, 5, 6 or 10) improves availability and protects against one or a few disk failures depending on the level. It does not protect against deletion, ransomware, misconfiguration, fires or theft. Real backups follow the 3-2-1-1-0 rule.

TL;DR

RAID ≠ backup: Protects from disk failure, not logic errors, ransomware or disasters.
3-2-1-1-0: 3 copies, 2 media types, 1 offsite, 1 offline/immutable, 0 restore errors.
Regular restore tests are mandatory — only tested backups are real backups.

What RAID actually solves — and what it doesn’t

Depending on the level, RAID tolerates the failure of one or more disks and keeps systems online. However, it preserves the same data errors across disks: accidental deletions, malware encryption, corrupted writes, or misconfigured scripts replicate immediately.

Availability: ✓ Better than single disk; hot-swap possible.
Data integrity: ✗ No protection from logical errors or massive corruption.
Disasters: ✗ No protection from fire, flood, theft, or power surge.

The 3-2-1-1-0 rule, briefly explained

3 copies

Production data + two backups. Versioning allows rolling back to a point before the incident.

2 media types

For example: primary storage + NAS/backup appliance + object storage (S3 compatible).

1 offsite

One copy outside your site protects against local disasters.

1 offline/immutable

Write-Once-Read-Many (WORM)/Object Lock or air-gap prevents tampering after the fact.

0 restore errors

Only regular restore tests prove backups are complete and usable.

In practice: a simple backup plan

Daily incrementals and weekly fulls (tune GFS as needed).
Enable versioning; retention e.g. 30/90/365 days per class of data.
Immutable S3 (Object Lock/WORM) or air-gap at least one copy.
Encrypt in transit and at rest; manage keys securely (KMS/HSM).
Quarterly restore tests: sample files, VMs, and full apps.
Monitoring & alerts for failed jobs, capacity, and RPO/RTO targets.

Checklist

Using RAID? Great — but still implement real backups with 3-2-1-1-0.
At least one immutable/offline copy in place and documented?
Last restore test documented (0 errors)? Next test scheduled?

Have us review your backup strategy

We help with planning, implementation and automation — on-prem to cloud, including immutable backups and restore tests.

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