On Apr 20, 2009, at 5:14 AM, André Berger wrote:
* Chuck Lever (2009-04-17):
Copying linux-nfs@xxxxxxxxxxxxxxx, please follow up there.
OK, here we go. If anyone here doesn't want to receive these
messages, please let me know.
It took me a while to get a tcpdump binary for the dbox2, hence the
delay and extensive quotes. The libc6 for tcpdump is itself located
on a NFS share.
[ ... ]
You could try capturing a raw packet trace of the initial mount and
a few
reads and write on the share. The clients negotiate the rsize and
wsize
settings with the server, and the packet dump would expose the
negotiated
values.
On your clients, use "tcpdump -s 0 -w /tmp/raw host" followed by
the DNS
name of your server. Then attach the raw pcap files to e-mail (as
long as
they are less than 100KB or so) and post them to linux-nfs@xxxxxxxxxxxxxxx
Here you go. The host "192.168.1.8 hg linkstation" is specified in
/etc/hosts.
For the sake of completeness, my router is a Linksys WRT54G
with Tomato firmware
<http://www.polarcloud.com/tomato_123>
and a MTU of 1492 throughout the network.
If there is anything I can do to help troubleshooting, please let me
know.
I got two copies of this e-mail. One has a 24KB PCAP file called
"raw" and the other has a 90KB file called "xap" that does not appear
to be a PCAP file.
I looked at "raw" and it's hard to make sense of it. I see both UDP
and TCP traffic, and both NFSv2 and NFSv3 requests. I guess this is
because tcpdump is on NFS. It would be better if you could copy the
tcpdump binary to a local file system on the client before running the
test to avoid the extra traffic.
You should avoid UDP on this network at all costs, especially if you
want to use large r/wsize. It's likely that this is the real
performance issue. Specify "proto=tcp" on your mount command line to
force the use of NFS/TCP. Otherwise IP packet fragmentation and
reassembly will cause dropped RPC requests, exacerbated by network
link speed mismatches and Ethernet frame collision on the half-duplex
links.
I believe the older 2.4-based NFS clients will use UDP by default.
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com--
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