ADIOS I/O type Limitations/On-going work

[jayeshkrishna]

-- DRAFT --
ADIOS I/O TYPE LIMITATIONS
SCORPIO

• Reading/writing with different I/O decompositions does not work
• Reading/writing with different number of MPI processes does not work
• Open to update a variable does not work
• Open to append an existing file does not work
• Overwriting existing attributes (with multiple pio_put_att calls on the same attribute) does not work
• Get of variables with dimensions >= 4D is not supported
• Redefine mode (to rename or delete an existing variable or attribute) is not supported
• To put/get a NetCDF variable (the variable type does not matter), the write buffer for pio_get_var and the read buffer for pio_get_var must use the same data type. If we use a double type write buffer to put a NC_INT variable and later use a float type read buffer to get it, the read buffer would contain incorrect values (missing required double to float type conversion)

ESMCI CIME

• CIME checks for NetCDF files for restart runs (requires files in the ".nc" extension). ADIOS "files" have ".bp" extension.
  ** As a workaround one can create dummy ".nc" files corresponding to ".bp" files to circumvent the CIME check
  UPDATE: For ADIOS file (BP directory) foo.nc.bp SCORPIO now creates a corresponding symbolic link foo.nc

E3SM

• MPAS does not support read using the ADIOS I/O type (the changes in env_run.xml XML file is not reflected in MPAS stream files)

SUGGESTED ENHANCEMENTS
E3SM

• Allow E3SM/SCREAM to write restart files and history files using different I/O types (e.g. Write restarts using ADIOS while writing history files using PnetCDF)