This is expected behaviour in Firedrake. Parallel vtu output consists of a collection of files, each containing data for a different part of the domain. It seems the most natural thing is for each process to write out data for the part of the domain it owns, otherwise we have to do extra moving of data. If we took this to the extreme of moving all the data onto one process, this would create a horrible serial bottleneck (and would be impossible if there was more data than would fit on a node).

Why is the large number of files a problem?

On 24 March 2017 at 08:52, Buesing, Henrik <HBuesing@eonerc.rwth-aachen.de> wrote:

Dear all,

Is it possible to reduce the number of output files in Firedrake when running in parallel? I am seeing an increase in the number of output files when increasing the number of processes used. Is this normal behavior?

Thank you!

Henrik

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Dipl.-Math. Henrik Büsing

Institute for Applied Geophysics and Geothermal Energy

E.ON Energy Research Center

RWTH Aachen University

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