Store back-ups offline and in a separate place (at a distance from their source if possible)

Providing a geographical distance from the storage media used for the back-ups ensures that an event such as theft, flood, fire or another destructive situation is not going to impact the capacity of the company to restore its data.

The back-ups should not be stored in an area that is close to the production data, because in the event of theft, fire, or other physical damage to the media, back-up media in the vicinity will also be burnt/stolen/etc., rendering the back-ups completely useless.

One method is to have a 3-2-1 back-up (one back-up online and available, one offline back-up kept locally, and a third offline kept on a remote site).