What are the prerequisites for creating a Fault Set?

Fault Sets are a logical subdivision within a Protection Domain used to increase availability (e.g., ensuring that the three copies of data reside in three different racks).

Predefined Protection Domain (Option B): Fault Sets exist inside a Protection Domain. You cannot create a Fault Set floating in the void; it must be assigned to a parent Protection Domain.

At least 3 nodes in the cluster (Option A): PowerFlex uses a mesh-mirroring architecture. To guarantee availability, the system generally requires a minimum of 3 Fault Sets (so that if one fails, the data can be rebuilt to the other two). Since a Fault Set must contain at least one node, this implies a minimum requirement of 3 nodes (one per Fault Set) to utilize the feature effectively.

Note on Option C: You typically define Fault Sets before creating Storage Pools or adding SDSs in a greenfield deployment. If Storage Pools already exist, converting to Fault Sets is complex/restricted, so "Existing Storage Pool" is not a prerequisite for creating the Fault Set structure itself.