Flex Files or, more properly, Flex Files Layout, is an extension to pNFS that allows the use of storage devices that require only a limited degree of interaction with the metadata server, and use already-existing protocols. It enables the aggregation of standalone NFSv3 and NFSv4 servers into a scale-out name space, and is part of the NFSv4.2 standard as described in the RFC 7862 specification.
Parallel NFS (pNFS) is part of the NFSv4.1 standard. It allows a separation between the metadata (onto a metadata server) and data (onto a storage device) for a file.
The Flex Files Layout is an extension to pNFS that allows the use of storage devices that require only a limited degree of interaction with the metadata server, and use already-existing protocols. It enables the aggregation of standalone NFSv3 and NFSv4 servers into a scale-out name space, and is part of the NFSv4.2 standard as described in the RFC 7862 specification.
Flex Files layout also supports client-side mirroring for file replication. See more here.
