[OpenAFS] Re: Performance problems seem to be coming back

Dale Pontius pontius@btv.ibm.com
Fri, 09 Sep 2011 15:36:16 -0400

On 09/09/2011 12:08 PM, Andrew Deason wrote:
> On Fri, 09 Sep 2011 09:41:10 -0400
> Dale Pontius<pontius@btv.ibm.com>  wrote:
>> Does anyone have advice on how to, as simply and automatically as
>> possible, monitor and log afs packet round trip times?
> This doesn't help for examining existing traffic, but if you want a
> really simple "afs ping" (or to be clear, what you're looking for is RTT
> for Rx packets, not AFS specifically), you can kind of use 'rxdebug
> -version'. Timing the execution of that isn't great to try to measure
> the actual rtt since there are other delays in there (e.g. starting the
> program itself) but it may be a useful relative measure, to see if the
> response starts to get slower or doesn't come back at all.
That's certainly better than using regular ping, since it's going to go through the AFS message queues, etc.  In fact, the coworker next door has been having some problems, and we tried this method in another window on another client machine right as his script slowed down, and saw a 20 second round trip time.

Which begs the question...  Is there a way to query the client and ask what servers it's talking with at the moment?  If I were going to set up some sort of automated monitoring loop, right now I'd have to feed it a list of directories, use "fs whereis" to turn that to a list of servers, unique-ify that list, then walk through it checking each server.  But which data I'm accessing changes all the time, and a "superset list" would probably have 2 dozen servers or more on it, whereas a more normal "working set" is probably more like a half-dozen servers.  I'd rather add a little traffic to traffic I'm already generating, not generate new traffic.

*** Oops, a little google, a little script, a little cmdebug, misc utils, and vos exam, and I've got a list of servers whose files are currently held in cache.

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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