The 3-2-1 Backup Rule for Ordinary Documents

The 3-2-1 rule comes from professional system administration, but it collapses into something a household can do in an afternoon: three copies of your documents, on two different kinds of storage, with one of them somewhere else physically. In practice that is the folder on your laptop, a copy in a cloud drive, and a copy on an external SSD that lives at a relative's house or in a desk drawer at work. Three, two, one. Notice that the laptop copy counts as one of the three, so you are only adding two things.

Cloud sync is not a backup, and this trips up more people than any other point. Sync propagates your mistakes: delete a folder, and it disappears everywhere within seconds. Ransomware encrypts your files, and the encrypted versions sync up cheerfully. What makes the third copy valuable is precisely that it is disconnected, an offline drive that is unplugged most of the time and therefore cannot receive your bad day. Plug it in quarterly, copy, unplug. Put a recurring reminder on the first Saturday of January, April, July, and October so the schedule is a date and not a vague intention.

Before a backup, spend ten minutes making the archive smaller and more useful, because a smaller archive is one you will actually copy to a slow external drive. Scanned documents are usually the bulk of the size. Run them through PdfWill compress, which keeps text selectable including Chinese, so the file stays searchable rather than becoming a blurry picture. Merge multi-part scans into single documents so the count of files drops. Remove blank and duplicate pages. There is no batch mode, so do this in a single focused sitting on your biggest offenders rather than trying to process everything.

Then the step nearly everybody skips: the restore drill. Once a year, pick three files at random from the backup, restore them to a temporary folder, and open them. This catches the failures that are otherwise invisible until the worst possible moment, such as an external drive that has silently died, a cloud folder that stopped syncing eight months ago, or an encrypted archive whose password you no longer remember. A backup you have never restored from is a hypothesis, not a backup. Fifteen minutes a year converts the hypothesis into a fact.

For sensitive material, encrypt before the copy leaves your control, not after. Use PdfWill protect with AES on tax records, medical documents, and identity papers, and note that PdfWill runs locally in your browser with zero uploads, so encryption happens on your own machine. Then store the password somewhere separate from the drive itself, which usually means a password manager, and make sure at least one trusted person can reach it. An encrypted offsite backup that nobody can open in an emergency has solved the wrong problem entirely.