On Mon, 10 Jun 2002, Thomas McLaughlin wrote:
> Thanks for the reply. 
> I have now tried turning on NFS  debugging as suggested and ran tcpdump
> but this did not seem to give any info on the problem. The logs entries just 
> stopped without any errors or looked like the file had copied ok with status
> set to ok. I can see from the tcpdump output that packets are fragmented
> when I user a buffwer size of 4096. 
> There is nothing even obviousy different in the log files/tcpdump output 
> when the copy does work (using a buffer size of 1024). In fact I can sometimes
> copy my test file once when I first restart nfs using the higher buffer size 
> and then I get the error each time I try and copy.

Hmmm, could you put the logs + tcpdumps on a web page somewhere so I can
have a look at them?

Preferably logs where the transfer works, and ones where it fails.


> It has been suggested that that it could be a problem with one of the network 
> cards/packets so should I not have seen problem with other applications such
> as ftp (which is ok)? Does this use a smaller packet size?

Sometimes. ftp uses TCP, which tries to fill packets for bulk transfer of
data.  However (by default) it wont cause IP fragmentation.  There are
also issues around slow-start and congestion avoidance, for example, which
limit the maximum transfer initially. But transferring any half-decent
sized files should "open the window" (ie get full available bandwidth).


> Both machines are running Mandrake 8.2 with no firewall software running 
> however my machine is running vmware and jabber daemon but does not
> appear to be causing problems.

AFAIK, vmware does have its own network driver, which does some clever
packet "injects" tricks. If possible, I'd try running without vmware, but
I doubt its the culprit here.

Paul.

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Particle Physics (Theory & Experimental) Groups                   Paul Millar 
Department of Physics and Astronomy                     [EMAIL PROTECTED]
University of Glasgow                                 [EMAIL PROTECTED]
Glasgow, G12 8QQ, Scotland             http://www.astro.gla.ac.uk/users/paulm 
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