Notes from the network

The 3-2-1 backup rule, and how to tell if your backups actually work

Having a backup isn’t the same as being able to recover. The rule that keeps one bad day from becoming permanent loss, and the restore test most businesses skip.

Topic
Backup & Security
Read time
2 min read
Published
29 Oct 2026
Author
Lestom Consulting

Every business says it has backups. Fewer have tried restoring from them. A backup you have never restored is a hope, not a plan, and the day you find out is usually the worst possible day.

01

The 3-2-1 rule

  • 3 copies of your data: the live copy plus two backups.
  • 2 different types of storage: for example a local backup device and a cloud service, so one failure can’t take out both.
  • 1 copy off-site: away from the office, so fire, flood or theft takes the building but not the data.

Ransomware adds one more requirement. At least one copy should be offline or immutable, meaning it cannot be changed or deleted for a set period, even by an administrator account. Ransomware deliberately looks for connected backups to encrypt them too.

02

Two numbers to agree on

  • How much work can you afford to lose? If the answer is “one day”, nightly backups are enough. If it’s “an hour”, they aren’t. This is your recovery point objective (RPO).
  • How long can you be down? Restoring a whole server from the cloud over an office connection can take far longer than people expect. This is your recovery time objective (RTO), and it decides whether you also need a fast local copy.

03

Don’t forget the cloud apps

Email and files in Google Workspace or Microsoft 365 feel safe because they live in the cloud. The provider keeps the service running, but deleted or overwritten data is largely your responsibility, and built-in retention is limited. If losing a mailbox would hurt, it belongs in your backup plan.

04

Test the restore, not the backup

A green tick on the backup report only tells you a job ran. Once a quarter, prove you can get data back:

  • Restore a handful of files from last week and open them.
  • Restore one complete mailbox or shared folder to a test location.
  • Once a year, time a full restore of your most important system and compare it with the downtime you said you could afford.
  • Write down what you did, so someone else could do it on a bad day.

05

Want a second pair of eyes?

Data backup and recovery is part of our Managed IT services: complete backup for your critical data, applications and systems, so a failure never becomes permanent loss. Book a free 15-minute call below to talk it through.

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