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?


Best regards,
Tomasz Wolski
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