The NFS Version 4 protocol specification disallows retransmission over the same TCP connection. Thus, this parameter primarily controls how quickly the client responds to certain events, such as detecting a forced unmount operation or detecting how quickly the server fails over to a new server.
Signed integer (32-bit)
600 (60 seconds)
0 to 231 - 1
10th of seconds
Yes, but this parameter is set when the file system is mounted. To affect a particular file system, unmount and mount the file system after changing this parameter.
TCP does a good job ensuring requests and responses are delivered appropriately. However, if the round-trip times are very large in a particularly slow network, the NFS version 4 client might time out prematurely.
Increase this parameter to prevent the client from timing out incorrectly. The range of values is very large, so increasing this value too much might result in situations where a retransmission is not detected for long periods of time.