By Martin Edwards

Last updated June 2018

Machines don’t work forever. Whether you keep your documents, photos and other files on your computer itself, or externally on a memory stick or disk, that storage will eventually fail and the data will be gone. Storage can fail for various reasons, regardless of its age or how expensive it was.

Further risks to your data include:

Backing up can help protect against all of the above. There are different kinds of backup, but the basic idea is the same: it’s safer to have two or more copies of something than just one. Consider also that to be most effective, each backup should be on a different disk or even in a separate place.

What backup is not

I meet people who say ‘I keep my photos safe by having them all on this memory stick instead of my computer’. This is a false sense of security because the memory stick may just as likely break or be lost, damaged or corrupted as the computer itself. Nothing is a backup if it’s your only copy, because no storage is perfect.

Rather, backup is effective because you have at least two copies of everything, and the chance that both your computer and backup device will fail on the same day is much lower than that of either failing by itself. If your computer fails, you fix it and recover from the backup; if the backup device fails, you resume backing up to a new one.

Local backup

Storing backups in your own home or office is called local backup. It has a one-off cost of around £50 for an external hard drive or memory stick. Then:

Both perform hourly backups. This might sound excessive until you realise the work you’d least want to lose is often your most recent.

They also retain older versions of files you modify, and even files you delete, for as long as space permits.

Online backup

Companies like Backblaze and SpiderOak offer online backup. This copies your data over the Internet to their servers, from which you can retrieve it even if both your computer and local backup are unavailable, for example due to fire or theft. A paid subscription is required.

Note: Naturally you should use a strong password on an online backup account, because in the same way that you can recover your data from anywhere, so can anyone else with the password.

File hosting

You might have heard of Dropbox, iCloud, OneDrive and so on and wonder how they fit in. These file hosting services were primarily designed for sharing stuff between multiple devices (e.g. your Mac and iPad) or with colleagues and friends.

Although they protect data from fire, flood and theft, they may not be as comprehensive as true online backup. For example, they may not keep old versions as you change a document, or retain copies of files you delete. Indeed, their main purpose is to keep data synchronised between multiple computers — delete a file on one device, and it will disappear from the rest. You should investigate and understand these potential limitations if you choose to rely on a file hosting service for backup.

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