Best practices · 12 October 2026 · OOXAAX
Backup: the 3-2-1 rule explained simply
Disk failure, theft, ransomware, fire: without a reliable backup, years of work can disappear. The 3-2-1 rule is simple and effective.
A backup is only useful on the day you need it, and on that day it is too late to make one. The 3-2-1 rule is the benchmark for protecting your data.
The 3-2-1 rule
- 3 copies of your data: the original and two backups.
- 2 different media: for example an external drive or NAS, and online storage.
- 1 off-site copy: kept in another location or in the cloud, to withstand theft, fire or flooding.
The most common mistakes
- Backing up to a drive that is always connected: ransomware will encrypt it along with the computer.
- Never testing a restore: an unreadable backup protects nothing.
- Forgetting the data on laptops and business phones.
Our recommendations
- Automate backups: anything that depends on people remembering will eventually be forgotten.
- Test a restore at least once a quarter.
- Keep several versions over time, so you can go back to before an error or an attack.
- Document the procedure: who backs up what, where, and how to restore.
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