By Martin Edwards

Published November 2016

Computer equipment doesn’t last forever. No matter where you keep your files – on your computer itself, or externally on a memory stick or disc – that storage will eventually fail and the data will be gone. Storage can fail suddenly and for a number of reasons, regardless of its age or how expensive it was.

Loss, theft, fire and natural disasters are also a risk. Or your files may be ‘corrupted’ by faults in software. Perhaps most distressingly, hackers may erase your data or, as we have seen more recently, use ‘ransomware’ to scramble it and demand money for its return. Finally, people make mistakes, as you’ll know if you’ve ever left something on a train or deleted an email by accident.

Backing up can help protect against all these threats. No matter which kind of backup you choose, the basic principle is the same: it’s safer to have two or more copies of something, in separate storage and ideally in separate places, than just one.

What backup isn’t

A common misconception is that a memory stick or portable hard drive, for example, is a safer place to keep things than a computer. I meet people who say “I keep my photos safe by having them all on this memory stick instead of the computer”. This is an illusion — the memory stick may just as likely get damaged or corrupted as the computer itself. Files on a memory stick, disk or whatever aren’t a backup if they are the only copy, as no type of 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

Backing up a modern computer may be easier and cheaper than you think. Traditionally we start with local backup, which has just a one-off cost: somewhere between £30 and £50 for an external hard drive or high-capacity memory stick.

If you have a PC with Windows 10, you can turn on File History to perform automatic local backups. The equivalent on a Mac is Time Machine. Both run hourly, which might sound excessive until you realise the work you’d least want to lose is often your most recent.

These backup systems also retain older versions of files you modify, and even files you delete, for as long as storage space permits.

Online backup

Companies like Backblaze, Carbonite and SpiderOak offer online or ‘cloud’ backup. These copy your data over the Internet to their servers, from which you can retrieve it even if both your computer and local backup are unavailable. A paid subscription is usually required.

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

Dropbox, iCloud and others

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 other kinds of backup. For example, they may not keep old versions as you edit a document, or keep 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.

Need help?

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