[gpfsug-discuss] Moving/copying files from one file system to another

Sean S Lee seanlee at tw.ibm.com
Wed Oct 30 12:30:26 GMT 2013

Hi Richard,


The cluster allocation method may provide better disk performance for some
disk subsystems in
relatively small installations. The benefits of clustered block allocation
diminish when the number
of nodes in the cluster or the number of disks in a file system increases,
or when the file system's
free space becomes fragmented. The cluster allocation method is the default
for GPFS clusters
with eight or fewer nodes and for file systems with eight or fewer disks.

The scatter allocation method provides more consistent file system
performance by averaging out
performance variations due to block location (for many disk subsystems, the
location of the data
relative to the disk edge has a substantial effect on performance). This
allocation method is
appropriate in most cases and is the default for GPFS clusters with more
than eight nodes or file
systems with more than eight disks.

Source: GPFS Administration and Programming Reference

Based on above it seems the scatter allocation would be more suitable for
your environment (more nodes, more disks), no?

The Web forum has few threads on GPFS copying, e.g. take a look at this:

I don't know if there's a better way or not.

If you don't change the allocation type, then you don't have to do anything
but add the disks and perhaps restripe.

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