...

join times (seconds):
each file was 1M data points

#files time
 1 0.0065
 2 0.0075
 3 0.0104
100 0.5900
500 1.2000

MPI Task Structure

To allow for scaling, many hdf5 files are written, one per "SRV" node.  The total number of SRV nodes is defined by the environment variable PS_SRV_NODES (defaults to 0).  These many hdf5 files are joined by psana into what appears to be one file using the hdf5 "virtual dataset" feature.