[gpfsug-discuss] AFM negative file caching

Venkateswara R Puvvada vpuvvada at in.ibm.com
Wed May 30 15:29:55 BST 2018


>I wasn’t sure if afmDirLookupRefreshInterval and 
afmFileLookupRefreshInterval would be the right thing if it’s a 
file/directory that doesn’t exist?

These refresh intervals applies to all the lookups and not just for 
negative lookups. For working around in AFM itself, you could try setting 
these refresh intervals to higher value if cache does not need to validate 
with home often.

~Venkat (vpuvvada at in.ibm.com)



From:   david_johnson at brown.edu
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   05/30/2018 06:14 PM
Subject:        Re: [gpfsug-discuss] AFM negative file caching
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Another possible workaround would be to add wrappers for these apps and 
only add the AFM based gpfs directory to the LD_LIBARY_PATH when about to 
launch the app. 

  -- ddj
Dave Johnson

> On May 30, 2018, at 8:26 AM, Peter Serocka <peserocka at gmail.com> wrote:
> 
> As a quick means, why not adding /usr/lib64 at the beginning of 
LD_LIBRARY_PATH?
> 
> (Not to get started on using LD_LIBRARY_PATH in the first place…)
> 
> 
> — Peter
> 
>> On 2018 May 30 Wed, at 13:52, Simon Thompson (IT Research Support) 
<S.J.Thompson at bham.ac.uk> wrote:
>> 
>> Hi All,
>> 
>> We have a file-set which is an AFM fileset and contains installed 
software.
>> 
>> We’ve been experiencing some performance issues with workloads when 
this is running and think this is down to LD_LIBRARY_PATH being set to the 
software installed in the AFM cache, e.g.
>> 
>> /gpfs/apps/somesoftware/v1.2/lib
>> 
>> Subsequently when you run (e.g.) “who” on the system, LD_LIBRARY_PATH 
is being searched for e.g. libnss_ldap, which is in /usr/lib64. We’re 
assuming that AFM is checking with home each time the directory is 
processed (and other sub directories like lib/tls) and that each time AFM 
is checking for the file’s existence at home. Is there a way to change the 
negative cache at all on AFM for this one file-set? (e.g as you might with 
NFS). The file-set only has applications so changes are pretty rare and so 
a 10 min or so check would be fine with me.
>> 
>> Thanks
>> 
>> Simon 
>> 
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>> 
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> 
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