[OpenAFS] Debugging a network performance problem that affects AFS

[Neil Davies]

A bone

rxdebug can be used to see either end of the connection (try it with  
the host/client addresses and ports reversed).

are there any VPNs involved? that makes fragmentation issues  
(especially if links are loaded) and their interaction with "full"  
buffers worth looking.

there are plenty of other steps possible after this - timed trace  
based analysis for example - but i doubt if those are of particular  
interest to the list and they would be more involved.

rx likes predictable round trip times (low variance in delay, low loss  
rates) - it is the lack of that I guess you are suffering from.

Neil

On 13 Jan 2011, at 20:24, Dale Pontius wrote:

> We're having intermittent network performance problems, and the  
> primary manifestation to us as users looks like "an OpenAFS  
> slowdown."  I'm wondering if it's possible to collect access time  
> statistics out of an OpenAFS Linux client.  A little time with  
> google and I see the "-enable_peer_stats" and "- 
> enable_process_stats" options when starting the client daemon, and  
> this very well may furnish the information that I need.  A  
> subsequent search gets me to the "rxdebug" document, though that  
> document appears to be server-centric as opposed to querying the  
> client.  Nor does it tell me what information I can collect or if  
> access time is part of that information - only mentioning serveral  
> parameters that it does collect.
>
> Can someone toss me a bone here - or a link?
>
> Thanks
> Dale Pontius
>
> -- 
> Dale Pontius
> Senior Engineer
> IBM Corporation
> Phone: (802) 769-6850
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> email: pontius@us.ibm.com
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