3-2-1-1-0

3-2-1-1-0 is a backup arrangement that is an advance on the original 3-2-1 strategy. The numbers stand for;

3 – Keep at least 3 copies of data

2 – On at least 2 different types of media

1 – With one backup copy offsite

1 – And one immutable copy

0 – Ensure zero errors with regular testing