[gpfsug-discuss] gpfs waiters debugging

[Frederick Stock]

Realize that generally any waiter under 1 second should be ignored.  In an 
active GPFS system there are always waiters and the greater the use of the 
system likely the more waiters you will see.  The point is waiters 
themselves are not an indication your system is having problems.

As for creating them any steady level of activity against the file system 
should cause waiters to appear, though most should be of a short duration.


Fred
__________________________________________________
Fred Stock | IBM Pittsburgh Lab | 720-430-8821
stockf at us.ibm.com



From:   Stijn De Weirdt <stijn.deweirdt at ugent.be>
To:     gpfsug-discuss at spectrumscale.org
Date:   06/06/2017 08:31 AM
Subject:        Re: [gpfsug-discuss] gpfs waiters debugging
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



hi bob,

waiters from RPC replies and/or threads waiting on mutex are most 
"popular".

but my question is not how to resolve them, the question is how to
create such a waiter so we can train ourself in grep and mmfsadm etc etc

we want to recreate the waiters a few times, try out some things and
either script or at least put instructions on our internal wiki what to 
do.

the instructions in the slides are clear enough, but there are a lot of
slides, and typically when this occurs offshift, you don't want to start
with rereading the slides and wondering what to do next; let alone debug
scripts ;)

thanks,

stijn

On 06/06/2017 01:44 PM, Oesterlin, Robert wrote:
> Hi Stijn
> 
> You need to provide some more details on the type and duration of the 
waiters before the group can offer some advice.
> 
> Bob Oesterlin
> Sr Principal Storage Engineer, Nuance
> 
> 
> 
> On 6/6/17, 2:05 AM, "gpfsug-discuss-bounces at spectrumscale.org on behalf 
of Stijn De Weirdt" <gpfsug-discuss-bounces at spectrumscale.org on behalf of 
stijn.deweirdt at ugent.be> wrote:
> 
> 
>     but we are wondering if and how we can cause those waiters ourself, 
so
>     we can train ourself in debugging and resolving them (either on test
>     system or in controlled environment on the production clusters).
> 
>     all hints welcome.
> 
>     stijn
>     _______________________________________________
> 
> 
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