Alex Still wrote:
> On Mon, Jun 21, 2010 at 4:38 PM, Nataraj <incoming-centos@xxxxxxx> wrote:
>
> [...]
>
>
>> Well, it's been a long time since I've done troubleshooting on large NFS
>> networks, but here's an idea...
>>
>> Are you seeing any kind of packet loss/retransmissions? Take a look at
>> netstat -s. When I last did this work it was with NFS over udp, but I
>> think retransmitted packets will cause more performance loss with large
>> packet sizes. I used to find machines with broken ethernet interfaces
>> that would cause these kinds of problems.
>>
>> Nataraj
>>
>
>
> Thanks guys for the feedback.
> I've done more tests : There are very very few retransmits (less than
> 0,01%) so I don't think that's what happening.
> The client still seems to be "waiting" for something between requests,
> very strange.
>
> On some servers this behavior returned despite rsize being set to 32k,vbhcs.org
> I had to set it to 8k to get reasonnable throughput. So there's
> definitly something fishy going on. This has been reported on over 20
> machines, so I don't think it's faulty hardware we're seeing.
>
> Any thoughts, ideas on how to debug this ?
>
> Best,
>
>
I would run tcpdump or other network sniffer. I don't know what your
network topology is, i.e. weather you have routers, complex switch
configurations etc in your network, but look for things like out of
order packets, duplicate packets tcp window sizes etc. If you have a
large or complex network topology, you may want to sniff at both the
server and client end. Even if your not an expert here, one thing you
can do is to setup a simple isolated client server example (could even
be with a virtual machine on your notebook or desktop) and sniff a
properly working connection and compare that with the situation where
you have problems.
Also make sure all your forward/reverse dns entries/service are running
correctly.
Nataraj
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
