Backups — The 3-2-1 Rule
If your laptop was destroyed tonight, could you carry on tomorrow?
- State the 3-2-1 backup rule
- Distinguish full, incremental and differential backups
- Perform a simple backup and restore
Overview
Backups protect Availability and Integrity. When ransomware encrypts your files, a fire destroys your laptop, or a phone falls in the sea, backups are the only thing that gets your data back. The 3-2-1 rule is the industry standard for anyone who cares about their data.
The 3-2-1 Rule
Keep 3 copies of your data, on 2 different media, with 1 copy stored offsite. Example: laptop hard drive + external USB drive + cloud backup.
Backup Types
Full backup copies everything. Incremental copies only what changed since the last backup — fast but restore is complex. Differential copies everything changed since the last full backup — a balance of speed and simplicity.
Testing Backups
An untested backup is a hope, not a plan. Restore a random file at least once a month to prove your backups actually work.
Delete and Restore
- In pairs, choose a test file on a shared drive.
- Delete it, then restore it from the class backup.
- Note how long the restore took and whether the file was identical.
- State the 3-2-1 rule.
Reveal answer
3 copies, 2 media types, 1 offsite.
- Why do we test restores, not just backups?
Reveal answer
A backup that cannot be restored is worthless.
- Which backup type is fastest to create — full, incremental or differential?
Reveal answer
Incremental — it copies only what changed since the last backup.
Design a 3-2-1 backup plan for your phone photos. Where would each copy live?