NFS version 4 Directory Notifications
Sun Microsystems
NFSv4 [RFC3530] contains within it a mechanism for the delegation of file data to a client. The intent of this feature is to reduce the necessary interaction between a client and server such that overall performance is improved. The same type of mechanism does not exist for directory contents and to determine validity of cached directory contents an NFSv4 client is left with polling the server to determine if updates have occurred. The proposal described here is for an NFSv4 minor version that would allow a client to register interest in a directory and to receive a callback RPC upon update of that directory. This type of interaction would reduce or eliminate the polling that occurs between client and server and improve scalability of the server's resources along with improved performance for the client's directory content caching.