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:
- Loss and theft
- Fire and natural disasters
- Corruption by faults in software
- Hackers and ‘ransomware’
- You (human error)
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
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.
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
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
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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surrounding villages. Visit my home page to find out more and get in touch.