Windows & PC Basics

A backup that will actually save you

The 3-2-1 rule in plain English, what to back up, and the test most people never do.

  • Level: Beginner
  • Time: about 9 minutes
  • Updated: 30 April 2026

Almost everyone we visit after a disaster had a backup of some kind. The ones who recover quickly are the ones who had more than one, and who had tested it.

  1. Follow the 3-2-1 rule

    Three copies of your data, on two different types of storage, with one copy off site. In practice: the working copy on your PC, a copy on an external drive, and a copy in the cloud.

  2. Turn on cloud backup for your documents

    In OneDrive settings, use Manage backup to include Desktop, Documents and Pictures. This covers the folders people actually save into, including the desktop full of files.

  3. Add a local image backup

    Cloud sync restores files but not a whole machine. Use imaging software to take a full copy to an external drive weekly, so a dead PC can be rebuilt rather than reinstalled from scratch.

  4. Keep one copy disconnected

    Ransomware encrypts anything it can reach, including an always-plugged-in external drive and a mapped network drive. Rotate two drives and keep the spare unplugged, ideally off site.

    Tip: For a business, versioned cloud backup with a retention period does this job automatically and is worth the modest monthly cost.

  5. Include the things people forget

    Accounts data files, email archives (.pst files), photos on phones, and password managers. Sage data does not live in Documents by default — check where your company file actually sits.

  6. Test a restore

    Once a quarter, restore a handful of files to a different folder and open them. A backup you have never restored from is a hope, not a backup.