[gpfsug-discuss] maxStatCache and maxFilesToCache: Tip "gpfs_maxstatcache_low".

[Philipp Grau]

Hello,

we have a two node NSD cluster based on a DDN system.  Currently we
run Spectrum Scale 5.0.4.1 in an HPC environment.

Mmhealth shows a tip stating "gpfs_maxstatcache_low". Our current settings are:

# mmdiag --config | grep -i cache
 ! maxFilesToCache 3000000
    maxStatCache 10000

maxFilesToCache was tuned during installion and maxStatCache is the
according default value.

After discussing this issue on the german spectumscale meeting, I
understand that it is difficult to give a formula on howto calulate
this values.

But I learnt that a FilesToCache entry costs about 10 kbytes of memory
and a StatCache entry about 500 bytes. And typically maxStatCache
should (obviously) be greater than maxFilesToCache. There is a average
100 GB memory usage on our systems (with a total of 265 GB RAM). 

So setting maxStatCache to at least 3000000 should be no problem. But
is that correct or to high/low?

Has anyone some hints or thoughts on this topic? Help is welcome.

Regards,

Philipp

-- 
 Philipp Grau               | Freie Universitaet Berlin   
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