> To use your own words, I fear its you who doesn't know what a backup is

Feel free to use my reputation, instead: when I say a system is backed up, data cannot be lost by that system being destroyed, because an independent copy always exists. This satisfies those whom it concerns, who put their money where their mouth is, whereas your more generous but insufficient definition would absolutely not be good enough.

When you assure a client that a system is backed up, which definition do they expect from you?