NFS server UPD or TCP

typically you want to use tcp instead of udp. Here is a note from RedHat admin guide:

The advantages of using TCP include the following:


Improved connection durability, thus less NFS stale file handles messages.

Performance gain on heavily loaded networks because TCP acknowledges every packet, unlike UDP which only acknowledges completion.

TCP has better congestion control than UDP (which has none). On a very congested network, UDP packets are the first packets that are dropped. This means that if NFS is writing data (in 8K chunks) all of that 8K must be retransmitted over UDP. Because of TCP's reliability, only parts of that 8K data are transmitted at a time.

Error detection. When a TCP connection breaks (due to the server being unavailable) the client stops sending data and restarts the connection process once the server becomes available. With UDP, since it's connection-less, the client continues to pound the network with data until the server reestablishes a connection.

The main disadvantage is that there is a very small performance hit due to the overhead associated with the TCP protocol.

thx for the reply tomorow i try a tcp connection for machines present in our wan, just to see the difference
because indeed i have some issue with computers that are remote since i migrate there homedirectory
from our unix server to the ns20. I've got a lot of retry when i look at the syslog

do use TCP - espeically with WAN clients

these old recommendations for UDP were from a time with slow servers clients

NFS over TCP is new to me; Can u sent me the doc u r refeering to ?

many thx for the help