Hi, while doing some I/O visualization we noticed that the attached program (MPI-IO.c) produces an I/O error under certain circumstances. The error messages printed by the program (MPI-IO.out) and pvfs2-server (pvfs2-server.out) are also attached.
The program basically writes and reads data using combinations of (non-)collective and (non-)contiguous I/O. It seems this error only occurs if we do non-collective, contiguous I/O (level 0) with multiple processes. Less processes and other levels work just fine. (The number of iterations our program does also seems to play a role; 2 iterations work, 3 produce the error.) To reproduce, create a default configuration for PVFS2 (data and metadata on localhost), start pvfs2-server and run the following: $ mpiexec -np 4 ./MPI-IO -i 10 -f pvfs2:///path/to/pvfs2 level0 # -i controls the number of iterations, -f the file that is written/read The error occured with PVFS 2.6.2, MPICH2 1.0.5p3 and on several different machines. We also noticed that a similar Flow error occurs if the server is low on free memory. Maybe in this case the error message should be modified to indicate the lack of memory? Regards, Michael
MPI-IO.c.gz
Description: GNU Zip compressed data
MPI-IO.out.gz
Description: GNU Zip compressed data
pvfs2-server.out.gz
Description: GNU Zip compressed data
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