I swear, not all my questions are NFS related. Just the weirdest ones. I have a VxWorks client that connects to a RHEL5 NFS server over UDP. The VxWorks device needs to copy a 6MB file into RAM to make something happen.
Anyways: connecting to the RHEL5 NFS server over TCP from another Linux machine, this file transfer takes a few seconds. Sadly, UDP is my only option because that's what was implemented in the kernel. Over UDP (both from the VxWorks client and a linux client mounting with just '-o udp'), I see unpredictable results: - Sometimes it will take a few seconds. - Sometimes it will take 5ish minutes. I tried setting the rsize/wsize on the Linux machine to slightly less than the MTU (<1500) and things worked at a reasonable rate again, consistently. Sadly, VxWorks has no facility to set rsize/wsize; the socket buffer is coded in the kernel at 10000 bytes. When things are acting slow, tcpdump on the RHEL5 NFS server shows bursty traffic being sent - chunks of packets being sent, then a few seconds pause, then some more chunks, then pause. When thing are acting fast, those seconds pause are no longer seconds of pause. Is there a server side setting I'm overlooking? Lots of googling says no, but maybe you have seen something I have not. Is there a network congestion thing I'm not taking into account? Not entirely impossible -- I don't have any visibility into the switches I'm using. The network team says they're not doing any prioritization of udp over tcp, which I would not expect or believe but I figured was worth asking. What else should I look at? Because, I'm lost. A million thanks in advance... - Pat _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
