Product : Nutanix, ECP [HCI]/5.11, Ultimate
Feature : Protection Capacity Overhead, Reads/Writes, Data Availability
Content Owner:  Herman Rutten
Summary
RF2 (2N) (primary): 100%
RF3 (3N) (primary): 200%
EC-X (N+1) (secondary): 20-50%
EC-X (N+2) (secondary): 50%
Details
EC-X (N+1): The optimal and recommended stripe size is 4+1 (20% capacity overhead for data protection). The minimum 4-node cluster configuration has a stripe size is 2+1 (50% capacity overhead for data protection).

EC-X (N+2): The optimal and recommended stripe size is 4+2 (50% capacity overhead for data protection). The minimum 6-node cluster configuration also has a stripe size is 4+2.

Because Nutanix Erasure Coding (EC-X) is a secondary feature that is only used for write cold data, with regard to an EC-X enabled Storage Container (=vSphere Datastore) the overall capacity overhead for data protection is always a combination of RF2 (2N) + EC-X (N+1) or RF3 (3N) + EC-X (N+2).