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An existing application can be investigated with respect to meta data usage. Let us assume an example job script for an MPI parallel application myexample.bin. For this example 16 MPI tasks are executed.

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --ntasks-per-node=8
#SBATCH --time=01:00:00
#SBATCH --partition=standard96

srun ./myexample.bin

For this example 16 MPI tasks are executed. Once you add the linux command strace to the job you create two files per linux process (MPI task). For this example 32 trace files are created. Large MPI jobs can create a huge number of trace files, e.g. a 128 node job with 128 x 96 MPI tasks created 24576 files. For this investigation we strongly recommend to reduce the MPI task number as far as possible. 

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --ntasks-per-node=8
#SBATCH --time=01:00:00
#SBATCH --partition=standard96

srun strace -ff -t -o trace -e open,openat ./myexample.bin

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