I've been watching this thread since the beginning, and now that y'all brought up networking, I believe I may have some useful suggestions in that arena.
Tom Lane <[EMAIL PROTECTED]> writes: > I'm thinking maybe one or both LAN cards have a problem with packets > exceeding a certain size. > Are all the intermediate network devices at layer 2 (switches)? If so, a simple look at counters for those ports involved would rule out or in any problems with those network devices. I'm sure that if you have an MTU of 1500 bytes across the board (on the hosts and the switch(es)) then you will not have a problem with fragmentation at that layer on 100 Mbit Ethernet. Make sure you're at 100baseTX-FDX. If you are using hubs, DO NOT use full duplex on your hosts. A hub can not function at full duplex, only half. If there are any intermediate layer 3 devices (routers), it's possible for them to fragment your packets. Verify the MTU on any of these devices as well as the appropriate duplex setting. Run netstat -s after passing a good bit of traffic between the hosts in question. Don't forget to do the math to determine error percentages. tcpdump could also reveal much about the packets such as their size and contents, whether they are fragments, if the DF bit is set, which host was the last to communicate, etc... A tcpdump along with your application trace may show you just the insight you needed to see. Do you have any packet filters between the devices? Make sure they're not dropping anything you need. I don't remember if NFS is one of these, but some things like to talk from high-port to high-port for [certain] things and high-port to low-port for other [certain] things. One thing I'd try that is a surefire way to determine if your network hardware is to blame, that is if you don't want to do all that crap above: Run your scenerio with your two devices connected via an ethernet crossover cable and NICs hard-coded to 100baseTX-FDX. It'll rule out everything except that cable and your NICs. Speaking of NICs, some [really old] NICs may report they are running at full-duplex when they really are not and can not. Incrementing port error counters (specifically, frame-check-sequence and collisions) will give this away, though. > > Is this purely a diagnostic suggestion? > > Well, if it changes anything then it would definitely show there's a > hardware problem to fix... > --peace, ~~Mike. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
