3-2-1 backup: the simple rule that protects your company’s data
Three copies, two media and one off-site. See how to apply the rule day to day and why testing restores matters more than making the copy.
· Josué Juca
- The 3-2-1 rule asks for 3 copies of your data, on 2 types of media, with 1 copy off-site.
- Making the copy is only half the job: test restores regularly.
- Keep at least one copy that ransomware cannot change.
Almost every company has some backup routine. The problem shows up when a server fails, a file is deleted by accident or ransomware encrypts everything, and you discover the copy was incomplete, on the same device or never tested.
What the 3-2-1 rule is
It is a simple, widely used practice to reduce the risk of losing data:
- 3 copies of your data: the original plus two backup copies.
- 2 different types of media, such as a NAS and a cloud service, so a single failure does not affect everything.
- 1 copy off-site, so a fire, theft or physical problem at the office does not take the backup with it.
What it looks like in practice
A common example for small and mid-sized companies: the file server holds the original data; every night it is copied to a NAS at the office; and that NAS replicates the data to the cloud. That makes three copies, two media types, one of them off-site.
A backup that was never restored is not a backup
Making the copy is only half the job. What guarantees recovery is knowing you can restore, and how long it takes. That is why your routine should include:
- Regular restore tests, actually recovering a few files and, from time to time, a whole system.
- Monitoring of the jobs, with an alert when a copy fails or goes stale.
- Several versions kept, and at least one disconnected or immutable copy that ransomware cannot change.
- A documented step-by-step, so anyone on the team can restore calmly in an emergency.
Two acronyms help define how much backup your company needs:
| Acronym | Question | What it defines |
|---|
| RTO | How fast must we be back up and running? | Restore speed and the type of solution |
| RPO | How much data can we afford to lose? | Backup frequency (hourly, daily...) |
If the server stopped right now, how fast would we be back and how much work would we lose? The answers point to the right strategy.
Where to start
List where your company’s important data lives, check how many copies exist of each one and where they are kept. If any of them is not off-site, or was never restored, that is the first thing to fix. We can help design and follow this process.