Three copies of anything you would cry over
The 3-2-1 backup rule: three copies, two kinds of media, one off site, and a restore you actually tested.
The 3-2-1 rule is older than cloud folders. Three copies of the data. Two different kinds of media. One copy off site. Photos, tax PDFs, the password export, the little archive of kids’ schoolwork: if you would swear at the ceiling when it vanished, it belongs in that pattern.
Why one disk is not a plan
The laptop dies. The house has a fire. Ransomware encrypts the disk and the USB drive you left plugged in. Sync to the cloud mirrors the deletion you did by accident, or the encryptor that renamed every file. A single live copy is a single story.
Two kinds of media means you are not betting on one vendor’s disk format. A drive in a drawer plus a cloud account is the usual home version. Tape is what shops used. You do not need tape. You need something that is not the same SSD.
Off site means a flood in the kitchen does not take every copy. Cloud counts if the account has a password you did not reuse and 2FA you did not skip. A drive at work or at a sibling’s house counts. A drive in the same backpack as the laptop does not.
Test the restore
Backups that have never been opened are a comfort object. Restore one folder this weekend. Time how long it takes. Notice whether you even remember the encryption password on the archive.
Versioning matters. Yesterday’s files should still exist after today’s disaster. Many cloud accounts keep a history if you pay for it or if you look for the setting. Turn that on for the folder that matters.
What not to back up blindly
Do not dump a whole disk image full of malware “just in case” and then restore it onto a clean machine. Restore documents. Reinstall the OS. That is slower and it is how you stop paying the ransom twice.
Three copies sounds like hoarding. It is cheaper than trying to buy the last ten years from a recovery forum.