One major issue is the maxFilesToCache and maybe the maxStatCache (though I 
hear that Linux negates the use of this parameter now?  I don’t quite 
remember).  Ganesha apparently likes to hold open a large number of files and 
this means that it will quickly fill up the maxFilesToCache.  When this happens 
the [gpfsSwapdKproc] process will start to eat up CPU time.  This is the daemon 
that tries to find a file to evict from the cache when a new file is opened.  
This overhead will also hurt performance.

IBM in a PMR we opened suggested setting this to something like 5 Million for 
the protocol nodes.  I think we started with 1.5 Million.  You have to be 
mindful of memory requirements on the token servers to handle the total sum of 
all maxFilesToCache settings from all nodes that mount the file system.

Of course the other, standard NFS tuning parameters for number of threads and 
NFS client mount options still should be adjusted too.

Hope that helps,

[] On Behalf Of Oesterlin, Robert
Sent: Sunday, October 16, 2016 7:06 PM
To: gpfsug main discussion list <>
Subject: [gpfsug-discuss] CES and NFS Tuning suggestions

Looking for some pointers or suggestions on what I should look at changing in 
Linux and/or GPFS "mmchconfg" settings to help boost NFS performance. Out of 
the box it seems "poor".

Bob Oesterlin
Sr Storage Engineer, Nuance HPC Grid


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