Primary Data This document defines the requirements which individual pNFS layout types need to meet in order to work within the parallel NFS (pNFS) framework as defined in RFC5661. In so doing, it aims to clearly distinguish between requirements for pNFS as a whole and those specifically directed to the pNFS File Layout. The lack of a clear separation between the two set of requirements has been troublesome for those specifying and evaluating new Layout Types. In this regard, this document updates RFC5661.