[gpfsug-discuss] Independent Inode Space Limit

Wayne Sawdon wsawdon at us.ibm.com
Fri Oct 23 16:25:33 BST 2015

>I also see that the first 1024 inodes are immediately allocated upon
>creation. I assume these are allocated to internal data structures and
>are a copy of a subset of the first 4038 inodes allocated for new file
>systems? It would be useful to know if these internal structures are
>fixed for independent filesets and if they are not, what factors
>determine their layout (for performance purposes).

Independent filesets don't have the internal structures that the file
system has. Other than the fileset's root directory all of the remaining
inodes can be allocated to user files.  Inodes are always allocated in full
metadata blocks. The inodes for an independent fileset are allocated  in
their own blocks. This makes fileset snapshots more efficient, since a
copy-on-write of the block of inodes will only copy inodes in the fileset.
The inode blocks for all filesets are in the same inode file, but the
blocks for each independent fileset are strided, making them easy to
prefetch for policy scans.

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