Almost everyone believes they are backed up. Most people are not, and they find out on the day the drive fails.

The 3-2-1 rule is the shortest useful summary of what actually protects files: three copies, on two kinds of media, with one of them outside the house. It comes from professional practice, but it applies perfectly well to an ordinary home with eighteen years of photos on it.

What each number means

Three copies. The original plus two backups. That sounds like a lot until you realise that two copies in the same room are really one copy, as far as a burst pipe is concerned.

Two kinds of media. For example the computer’s internal drive plus an external drive. Or an external drive plus cloud storage. The point is to avoid putting both copies in the same technological basket: drives of the same model, bought the same day, have an unfortunate habit of dying the same year.

One copy off site. This is the part nearly everyone skips, and it is the only one that survives a fire, a theft or a flood. An external drive sitting beside the computer survives none of those three.

Why the third copy is the one that counts

A hard drive dying is annoying. You lose an afternoon, sometimes some money, and you move on.

A basement flood, a kitchen fire or a break-in is a different category. In those cases the computer and the external drive go together, because they were on the same desk. Every family photo disappears at once, and there is no recovery service for that.

There is also the modern case: ransomware that encrypts the computer’s files, then the permanently connected external drive too, because as far as it is concerned that is just another folder. A copy that is offline or off site is the only one that escapes.

What this looks like in a real home

Three arrangements that satisfy the rule, from simplest to most complete.

The minimum. Your files on the computer. An automatic backup to a cloud service. An external drive plugged in once a month, then put back in a drawer. Three copies, two kinds of media, one of them not in the house at the moment something happens.

The comfortable one. The computer, an always-connected external drive running an automatic daily backup, and cloud storage on top. You recover an accidentally deleted file in thirty seconds from the drive, and the online copy covers everything else.

The family one. The same as above, but with a second external drive living at an adult child’s place or at the cottage, swapped at Christmas and again in the summer. It sounds homemade. It is extremely effective, and it costs nothing extra per month.

What to back up, and what is not worth the space

Backing up “the whole computer” feels reassuring, but it is not always the most useful thing. What genuinely matters falls into two categories.

The irreplaceable. Photos and videos. Documents. Email, if it is stored locally rather than with a provider. Scans of important paperwork. Work in progress. Accounting files. Anything that, if it vanished, could not be downloaded again or recreated.

The merely tedious to rebuild. Passwords saved in the browser, bookmarks, the settings of an application you spent months tuning, a music library. Nothing tragic, but an evening gone.

What does not deserve backup space: the operating system, downloaded applications, films and music bought online, games. All of that reinstalls. A full system image has its uses for getting running again quickly, but it is not what protects your memories.

The classic trap is the desktop folder. Plenty of people work directly there, and plenty of backup tools do not include the desktop by default. Check that specific point.

Mac or Windows: what you already have

You very likely already have a backup tool installed without knowing it.

On a Mac, Time Machine is built in and does the job well. Plug in an external drive, macOS offers to use it, and from then on it backs up hourly while keeping history. It is one of the few consumer features that genuinely works without supervision.

On Windows, the picture is muddier. File History has existed for years but mostly covers personal folders, and Microsoft has changed strategy several times. The “Windows Backup” app backs up to OneDrive, limited by whatever space your plan includes. Many people end up with something partially switched on that does not cover what they assume it does.

In both cases the built-in tool handles the local copy. It does not handle the off-site copy, which still has to be added.

How long the first one takes

This is the question that makes people abandon the job half done.

To a USB external drive, budget roughly an hour per 100 GB. A 500 GB photo library will therefore take most of an afternoon. After that, subsequent backups only copy what changed and take a few minutes.

To the cloud, your upload speed decides, and upload is almost always the slow half of a home internet plan. At 20 Mbit/s up, 500 GB takes about three days running continuously. That is not a typo: you start the first online backup and let it run over a weekend. After that it is near-instant.

Keep the computer plugged in and stop it from sleeping during that first pass. It is the single most common reason a first backup never finishes.

Does cloud storage count as a backup?

Yes and no, and the distinction is worth understanding.

A sync service like iCloud, OneDrive or Google Drive keeps your files identical across your devices. That is convenient, but it is a mirror: delete a folder on the computer and it disappears everywhere, including online. Sync faithfully reproduces your mistakes.

A backup service also keeps previous versions, often thirty days or more. That is what lets you say “give me back the folder as it was last Tuesday”.

Most sync services do offer a trash and a version history, which brings them closer to a real backup. But the window is short and the settings are buried. If your photos exist only in iCloud, you have a copy, not a backup.

What it costs

A 2 TB external drive runs around $90 and typically lasts four to six years. Cloud plans run roughly $3 to $15 a month depending on space, and many people are already paying for one without knowing it, because it came bundled with the phone.

Put another way: protecting an entire digital life costs less per month than a weekly coffee. Lab data recovery, when it is even possible, runs into the hundreds of dollars and comes with no guarantee.

The mistakes we see most

The external drive that never gets plugged back in. Bought with the best intentions, used twice, then put away. A backup from three years ago is a backup from three years ago.

The backup that quietly stopped. The drive got disconnected, the subscription lapsed, the password changed. Nothing flashes, nobody is told, and everyone carries on believing it is handled.

Forgotten phone photos. The phone is now the device holding the most memories, and it is the one people back up least.

One copy, very neatly stored. A drive carefully placed beside the computer is still a drive beside the computer.

The only thing that proves it works

A backup is not a backup until you have restored a file from it.

Do the test today: pick a document at random, open your backup, and restore it somewhere else. If you cannot manage that in ten minutes without help, your backup is not ready for the day you genuinely need it, and on that day you will already be upset.

That is a subject for another article, because it is the step almost everyone skips.

Where to start this week

Find where your important files actually live. For most people: documents, desktop, photos, and the phone.
Turn on an automatic backup. Time Machine on a Mac, File History on Windows, or an online service.
Add the off-site copy. Cloud, or a drive that lives somewhere else.
Restore one file to check.
Put a note in the calendar a year from now to test it again.

If you would rather have someone set this up and run the restore test in front of you, that is exactly what our data and backup service covers. We can also do the software side remotely, with no visit needed, at the same rate as an on-site visit.