The BSI has just named it measure no. 1 again: Data needs backups. Modern backups not only protect against data loss, but must also be protected against manipulation or unintentional deletion, for example, by ransomware, as current attacks specifically attack all accessible backups first and render them unusable. A number of technologies are available for protection, all of which promise one thing: Making backups invulnerable. We take a look at the individual options and show the advantages and disadvantages.