[gpfsug-discuss] Same file opened by many nodes / processes

[Yaron Daniel]

Hi

Do u run mmbackup on snapshot , which is read only ?

 
Regards
 


 
 
Yaron Daniel
 94 Em Ha'Moshavot Rd

Storage Architect ? IL Lab Services (Storage)
 Petach Tiqva, 49527
IBM Global Markets, Systems HW Sales
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From:   Peter Childs <p.childs at qmul.ac.uk>
To:     "gpfsug-discuss at spectrumscale.org" 
<gpfsug-discuss at spectrumscale.org>
Date:   07/10/2018 05:51 PM
Subject:        [gpfsug-discuss] Same file opened by many nodes / 
processes
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



We have an situation where the same file is being read by around 5000
"jobs" this is an array job in uge with a tc set, so the file in
question is being opened by about 100 processes/jobs at the same time.

Its a ~200GB file so copying the file locally first is not an easy
answer, and these jobs are causing issues with mmbackup scanning the
file system, in that the scan is taking 3 hours instead of the normal
40-60 minutes.

This is read only access to the file, I don't know the specifics about
the job.

It looks like the metanode is moving around a fair amount (given what I
can see from mmfsadm saferdump file)

I'm wondering if we there is anything we can do to improve things or
that can be tuned within GPFS, I'm don't think we have an issue with
token management, but would increasing maxFileToCache on our token
manager node help say?

Is there anything else I should look at, to try and attempt to allow
GPFS to share this file better.

Thanks in advance

Peter Childs

-- 
Peter Childs
ITS Research Storage
Queen Mary, University of London
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