Block failure protection can be achieved by assigning chassis to different Protection Domains (aka Zones).

Protection Domains: Protection domains at the chassis level allow scaling of NetApp HCI clusters in such a way that
the failure of an entire chassis can be sustained even if there is more than one storage node in the chassis. The minimum allowed configuration is 3 chassis with 2 storage nodes each. The system automatically lays out data correctly when the configuration is compatible with Protection domains.

Beginning with Element OS 12.0, protection domain layouts can be customized to cover zones of storage nodes within a rack, or between multiple racks. This enables more flexibility in data resiliency and improves storage availability, especially in large scale installations.