Backing up the household's files with the 3-2-1 rule

Photos, scanned papers, tax files and the household's records live on computers and phones, and a single backup may not be enough to keep them safe. The 3-2-1 rule raises the chance of recovering a file that's lost or corrupted, because no single failure reaches every copy.

The 3-2-1 rule

• Keep 3 copies of any important file. That's the original and two backups.
• Keep them on 2 different kinds of storage. Each kind is exposed to different hazards.
• Keep 1 copy offsite. That means somewhere outside the house.

A second copy on the same computer

Keeping a backup on the computer's own hard drive is quick and needs no extra equipment. But if that drive is damaged, stolen or corrupted, the original and the backup go together. A backup that updates itself automatically can also copy corruption or malware from the original files into the backup.

Cloud storage

A cloud backup service keeps a copy on the provider's servers, reached over the internet. It protects against some of the worst cases, such as a natural disaster or the failure of a device at home, and it counts as the offsite copy. You give up most of your control over the data, and you know little about the provider's systems. Before you trust one with important files, read its service agreement for how it protects your data. Look for a provider that encrypts your data and sends it over a secure connection.

Removable drives

An external hard drive, a USB flash drive or an SD card holds a copy you control directly. Keeping it separate from the computer protects it from online attackers and from power surges. Because it's portable, it's also easy to lose or have stolen. Protect it with a password, encrypt it where you can, and unplug it from the computer when the backup is done. Store it somewhere secure.

Flash drives and SD cards have no moving parts, so they're small, resist shocks and read data quickly. Writing to them over and over eventually wears them out. Many come with built-in password protection and encryption.

An annotated example

What to do next

List the files the household couldn't replace, such as photos, scanned IDs and policies, and tax returns. Then check where each one lives today against the 3-2-1 rule. Every few months, open a file from each backup to check that it holds the latest version.