[gpfsug-discuss] Number of Inodes in chained AFM Caches

[Luke Raimbach]

Hi All,

We have a situation where we are chaining AFM caches together: local update on the end of a read-only cache of a non GPFS NFS share.

Essentially we have an intermediate read-only cache which can pull multiple data sources in quickly over the local network at the remote site, staging the data for WAN transfer into the ultimate destination which is a local update cache.

In our first set of test runs, I am seeing a large discrepancy in the number of allocated inodes in the intermediate cache and the final local-update cache.

We have sized the intermediate read-only caches to contain about 10% more "Maximum number of inodes" than the source NFS share (to accommodate any growth that happens while we transfer the data). We have also size the final local-update cache to have the same maximum number of inodes.

The number of allocated inodes in the intermediate read-only cache shows the number of files in the source NFS share. However in the local-update shares, I always see 1500800 allocated and am concerned that the destination is not reading all the file-system metadata from the intermediate cache.

Any ideas what could be going on here?

Cheers,
Luke.

Luke Raimbach​
Senior HPC Data and Storage Systems Engineer,
The Francis Crick Institute,
Gibbs Building,
215 Euston Road,
London NW1 2BE.

E: luke.raimbach at crick.ac.uk
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