[gpfsug-discuss] Inode scan optimization
Frederick Stock
stockf at us.ibm.com
Thu Feb 8 12:44:35 GMT 2018
You mention that all the NSDs are metadata and data but you do not say how
many NSDs are defined or the type of storage used, that is are these on
SAS or NL-SAS storage? I'm assuming they are not on SSDs/flash storage.
Have you considered moving the metadata to separate NSDs, preferably
SSD/flash storage? This is likely to give you a significant performance
boost.
You state that using the inode scan API you reduced the time to 40 days.
Did you analyze your backup application to determine where the time was
being spent for the backup? If the inode scan is a small percentage of
your backup time then optimizing it will not provide much benefit.
Fred
__________________________________________________
Fred Stock | IBM Pittsburgh Lab | 720-430-8821
stockf at us.ibm.com
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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