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8.2. pNFS

Support for Parallel NFS (pNFS) as part of the NFS v4.1 standard is available as of Red Hat Enterprise Linux 6.4. The pNFS architecture improves the scalability of NFS, with possible improvements to performance. That is, when a server implements pNFS as well, a client is able to access data through multiple servers concurrently. It supports three storage protocols or layouts: files, objects, and blocks.

Note

The protocol allows for three possible pNFS layout types: files, objects, and blocks. While the Red Hat Enterprise Linux 6.4 client only supported the files layout type, Red Hat Enterprise Linux 7 supports the files layout type, with objects and blocks layout types being included as a technology preview.

pNFS Flex Files

Flexible Files is a new layout for pNFS that enables the aggregation of standalone NFSv3 and NFSv4 servers into a scale out name space. The Flex Files feature is part of the NFSv4.2 standard as described in the RFC 7862 specification.
Red Hat Enterprise Linux can mount NFS shares from Flex Files servers since Red Hat Enterprise Linux 7.4.

Mounting pNFS Shares

  • To enable pNFS functionality, mount shares from a pNFS-enabled server with NFS version 4.1 or later:
    # mount -t nfs -o v4.1 server:/remote-export /local-directory
    After the server is pNFS-enabled, the nfs_layout_nfsv41_files kernel is automatically loaded on the first mount. The mount entry in the output should contain minorversion=1. Use the following command to verify the module was loaded:
    $ lsmod | grep nfs_layout_nfsv41_files
  • To mount an NFS share with the Flex Files feature from a server that supports Flex Files, use NFS version 4.2 or later:
    # mount -t nfs -o v4.2 server:/remote-export /local-directory
    Verify that the nfs_layout_flexfiles module has been loaded:
    $ lsmod | grep nfs_layout_flexfiles

Additional Resources

For more information on pNFS, refer to: http://www.pnfs.com.