[OpenAFS] Debugging a network performance problem that affects AFS

[Dale Pontius]

No VPNs involved here.  I do run AFS over vpn occasionally, but on those 
times my response is sufficiently swamped by WAN considerations that I 
don't even think about performance.  For now I'm talking purely local 
response.

Your comment about "predictable round trip times" rings a bell.  We're 
seeing occasional spikes in ping response time, and feel that that would 
be indicative of AFS and general network problems.  But I was hoping to 
nail something down to, "Here, I found the problem showing up in a 
measurable way in AFS!"

Dale
On 01/13/2011 03:51 PM, Neil Davies wrote:
> 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
>> Tie-Line: 446-6850
>> email: pontius@us.ibm.com
>>
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-- 
Dale Pontius
Senior Engineer
IBM Corporation
Phone: (802) 769-6850
Tie-Line: 446-6850
email: pontius@us.ibm.com

This e-mail and its attachments, if any, may contain confidential and privileged material for the sole use of the intended recipient. Any review, use, distribution or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive for the recipient), please contact the sender by reply e-mail and delete all copies of this message from your system without copying it and notify sender of the misdirection by reply e-mail.