[gpfsug-discuss] Inode scan optimization - (Tomasz.Wolski at ts.fujitsu.com )

[Marc A Kaplan]

Please clarify and elaborate ....  When you write "a full backup ... takes 
60 days"  - that seems very poor indeed.
BUT you haven't stated how much data is being copied to what kind of 
backup media nor how much equipment or what types you are using... Nor 
which backup software... 

We have Spectrum Scale installation doing nightly backups of huge file 
systems using the mmbackup command with TivoliStorageManager backup, using 
IBM branded or approved equipment and software.



From:   "Tomasz.Wolski at ts.fujitsu.com" <Tomasz.Wolski at ts.fujitsu.com>
To:     "gpfsug-discuss at spectrumscale.org" 
<gpfsug-discuss at spectrumscale.org>
Date:   02/08/2018 05:50 AM
Subject:        [gpfsug-discuss] Inode scan optimization
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Hello All,
 
A full backup of an 2 billion inodes spectrum scale file system on 
V4.1.1.16 takes 60 days.
 
We try to optimize and using inode scans seems to improve, even when we 
are using a directory scan and the inode scan just for having a better 
performance concerning stat (using gpfs_stat_inode_with_xattrs64). With 20 
processes in parallel doing dir scans (+ inode scans for stat info) we 
have decreased the time to 40 days.
All NSDs are dataAndMetadata type.
 
I have the following questions:
·         Is there a way to increase the inode scan cache (we may use 32 
GByte)? 
o   Can we us the “hidden” config parameters
§     iscanPrefetchAggressiveness 2
§     iscanPrefetchDepth 0
§     iscanPrefetchThreadsPerNode 0
·         Is there a documentation concerning cache behavior?
o   if no, is the  inode scan cache process or node specific?
o   Is there a suggestion to optimize the termIno parameter in the 
gpfs_stat_inode_with_xattrs64() in such a use case?
 
Thanks! 
 
Best regards,
Tomasz Wolski_______________________________________________
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