/FILEIDS [= {UNIQUE | NONUNIQUE}]

    Optional. Default: /FILEIDS=UNIQUE.

    With UNIQUE, the client uses the file name and 32-bit NFS file ID
    when processing the directory information returned by the server
    to determine whether cached information is valid.

    With NONUNIQUE, the client uses the file handle instead of the
    file ID. This can refresh directory entries in the client's cache
    more quickly. However, this can degrade performance because the
    client must issue additional RPC requests to get the file handle.