3-2-1 Rule

3-2-1 Rule – The storing of a backup in three separate places to ensure one of the versions can be used to recover the backed up data in case the original data is lost. The 3-2-1 rule says that you should have at least three versions of your backup on two separate media types, one of which should be in a separate location. This protects against drive failure, a media failure and a location failure.