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The reason I think the metanode is moving around is I'd done a limited amount of trying to track it down using "mmfsadm saferdump file" and it moved before I'd tracked down the correct metanode. But I might have been chasing ghosts, so it may be operating normally
and nothing to worry about.<br>
<br>
The user reading the file only has read access to it from the file permissions, <br>
<br>
Mmbackup has only slowed down while this job has been running. As I say the scan for what to backup usally takes
<a href="tel:40-60">40-60</a> minutes, but is currently taking 3-4 hours with these jobs running. I've seen it take 3 days when our storage went bad (slow and failing disks) but that is usally a sign of a bad disk and pulling the disk and rebuilding the RAID
"fixed" that straight away. I cant see anything like that currently however.<br>
<br>
It might be that its network congestion were suffering from and nothing to do with token management but as the mmpmon bytes read data is running very high with this job and the load is spread over 50+ nodes it's difficult to see one culprit. It's a mixed speed
ethernet network mainly 10GB connected although the nodes in question are legacy with only 1GB connections (and 40GB to the back of the storage.<br>
<br>
We're currently running <a href="tel:4.2.3-8">4.2.3-8</a><br>
<br>
Peter Childs<br>
Research Storage<br>
ITS Research and Teaching Support<br>
Queen Mary, University of London<br>
<br>
---- IBM Spectrum Scale wrote ----<br>
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<div><font size="3" face="Arial">What is in the dump that indicates the metanode is moving around? Could you please provide an example of what you are seeing?</font><br>
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<font size="3" face="Arial">You noted that the access is all read only, is the file opened for read only or for read and write?</font><br>
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<font size="3" face="Arial">What makes you state that this particular file is interfering with the scan done by mmbackup? Reading a file, no matter how large should significantly impact a policy scan.</font><br>
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<font size="3" face="Arial">What version of Spectrum Scale are you running and how large is your cluster?</font><br>
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<font size="2" face="sans-serif">Regards, The Spectrum Scale (GPFS) team<br>
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<br>
<font size="1" color="#5f5f5f" face="sans-serif">From: </font><font size="1" face="sans-serif">Peter Childs <p.childs@qmul.ac.uk></font><br>
<font size="1" color="#5f5f5f" face="sans-serif">To: </font><font size="1" face="sans-serif">"gpfsug-discuss@spectrumscale.org" <gpfsug-discuss@spectrumscale.org></font><br>
<font size="1" color="#5f5f5f" face="sans-serif">Date: </font><font size="1" face="sans-serif">07/10/2018 10:51 AM</font><br>
<font size="1" color="#5f5f5f" face="sans-serif">Subject: </font><font size="1" face="sans-serif">[gpfsug-discuss] Same file opened by many nodes / processes</font><br>
<font size="1" color="#5f5f5f" face="sans-serif">Sent by: </font><font size="1" face="sans-serif">gpfsug-discuss-bounces@spectrumscale.org</font><br>
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<tt><font size="2">We have an situation where the same file is being read by around 5000<br>
"jobs" this is an array job in uge with a tc set, so the file in<br>
question is being opened by about 100 processes/jobs at the same time.<br>
<br>
Its a ~200GB file so copying the file locally first is not an easy<br>
answer, and these jobs are causing issues with mmbackup scanning the<br>
file system, in that the scan is taking 3 hours instead of the normal<br>
40-60 minutes.<br>
<br>
This is read only access to the file, I don't know the specifics about<br>
the job.<br>
<br>
It looks like the metanode is moving around a fair amount (given what I<br>
can see from mmfsadm saferdump file)<br>
<br>
I'm wondering if we there is anything we can do to improve things or<br>
that can be tuned within GPFS, I'm don't think we have an issue with<br>
token management, but would increasing maxFileToCache on our token<br>
manager node help say?<br>
<br>
Is there anything else I should look at, to try and attempt to allow<br>
GPFS to share this file better.<br>
<br>
Thanks in advance<br>
<br>
Peter Childs<br>
<br>
-- <br>
Peter Childs<br>
ITS Research Storage<br>
Queen Mary, University of London<br>
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