Support for Application IO Hints

This document proposes a new IO_ADVISE operation for NFSv4.2 that clients can use to communicate expected I/O behavior to the server. By communicating future I/O behavior such as whether a file will be accessed sequentially or randomly, and whether a file will or will not be accessed in the near future, servers can optimize future I/O requests for a file by, for example, prefetching or evicting data. This operation can be used to support the posix_fadvise function as well as other applications such as databases and video editors.