Most people have some kind of backup. The problem is that they discover its gaps on the day of the failure — when it turns out the copy covered the desktop but not the email, or that the backup drive sat next to the computer that was flooded.
The 3‑2‑1 rule in plain terms
3 copies of the data, on 2 different media, with 1 kept outside the building. At home that means: the original on the computer, a copy on an external drive, a second copy in the cloud. In a small business: data on a server or computer, a copy on a separate drive and a remote copy.
| Element | At home | In a small business |
|---|---|---|
| Original | Computer disk, phone | Computers, server, network drive |
| Local copy | External drive connected for the backup | Backup server or NAS in another room |
| Off-site copy | Cloud with versioning | Remote copy or a drive rotated off site |
| Protects against | Disk failure, deleted file | Also fire, theft, encryption of data |
Sync is not a backup
Cloud storage that instantly mirrors every change is convenient — and dangerous. Delete a folder and it disappears in the cloud. Let malware encrypt it and the encrypted version travels upward. The cloud becomes a backup only when it offers versioning and a bin with a long enough retention period.
What to actually copy
Start with what cannot be recreated. The system and applications can be reinstalled. Wedding photos, project documentation and a client database cannot.
- Documents, invoices, contracts and scans.
- Photos and videos — including those on the phone.
- Email, if your client downloads messages and removes the server copy (POP3).
- Application databases: accounting, warehouse, CRM, industry software.
- Configurations and licence keys that take half a day to find after a failure.
- Passwords — ideally in a password manager whose database is also backed up.
How often
The answer comes from one question: how much work can you afford to lose? If it is an hour, the backup must be frequent and automatic. If it is a week, a weekly copy is enough. There is no universally correct frequency, only your tolerance for loss.
The restore test — the only proof it works
- Pick a random file from a month ago and restore it to the desktop.
- Check that it opens correctly and contains what it should.
- Measure how long finding and restoring it took.
- In a company: once a year restore a full application database on a test machine.
- Note the result and the date — that is the only documentation that matters after a failure.
Ransomware: why the copy must be separated
Encrypting malware looks for everything the computer can reach — including a connected external drive and a mapped network drive. A copy that is permanently attached stops being a copy at the worst possible moment. Options: a drive connected only during the backup, a remote copy with separate credentials, or storage with a write-lock for a set period.
A backup is the cheapest insurance in IT — provided it is automatic and tested. To have it set up once and properly, see backups and security.