When reviewing the actual protection output of N+4/2, what does the number “4” represent?

When reviewing the actual protection output of N+4/2, what does the number “4” represent?
A . FEC stripe units per stripe
B . Hard drives used per stripe
C . Volume stripes per file system
D . FEC stripe units per file system

Answer: A

Explanation:

It’s OneFS FEC protection nomenclature for our "hybrid" protection polices. More generally, it’s written as: N+M/b where "N" is the number of data stripe units in a stripe, "M" is the number of FEC stripe units in a stripe, and "b" is the number of stripe units in a stripe which are allowed to reside on the same node.

Reference: https://www.dell.com/community/Isilon/Isi-get-output/td-p/7085467