[OpenAFS] Debugging a network performance problem that affects
Fri, 14 Jan 2011 08:27:23 -0500
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
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!"
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.
> 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?
>> Dale Pontius
>> Dale Pontius
>> Senior Engineer
>> IBM Corporation
>> Phone: (802) 769-6850
>> Tie-Line: 446-6850
>> email: email@example.com
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