Changes between Version 3 and Version 4 of PnetcdfAndNetcdf4


Ignore:
Timestamp:
01/08/15 12:56:53 (4 years ago)
Author:
wkliao
Comment:

add note for parallel I/O on CDF-1 and 2 file formats

Legend:

Unmodified
Added
Removed
Modified
  • PnetcdfAndNetcdf4

    v3 v4  
    55Some software engineering gave NetCDF-4 the concept of a separation between interface and file format (netCDF API, legacy netCDF or new HDF5 file format).  Soon, UCAR extended this interface and gave NetCDF-4 the ability to use PnetCDF.   Now, with some caveats, the classic netCDF API can read and write the classic netCDF file format either using the classic netCDF library or our PnetCDF library. 
    66 
    7 We think this is terrific, and in no way has UCAR usurped or challenged PnetCDF with this move. Instead, UCAR has provided a valuable option to applications developers.  In order to transition to parallel I/O, the typical "file per process" or "all I/O from rank 0" approaches need to be re-thought, no matter which underlying library will carry out the I/O.  Applications accustomed to serial netCDF can try out pnetcdf while still using an API familiar to them.  If they want to use some of the more sophisticated PnetCDF features, or try out pnetcdf down the road, only minor edits to the names of the functions will be needed -- the application has already done the hard work of domain decomposition. 
     7We think this is terrific, and in no way has UCAR usurped or challenged PnetCDF with this move. Instead, UCAR has provided a valuable option to applications developers.  In order to transition to parallel I/O, the typical "file per process" or "all I/O from rank 0" approaches need to be re-thought, no matter which underlying library will carry out the I/O.  Applications accustomed to serial netCDF can try out PnetCDF while still using an API familiar to them.  If they want to use some of the more sophisticated PnetCDF features, or try out PnetCDF down the road, only minor edits to the names of the functions will be needed -- the application has already done the hard work of domain decomposition. 
    88 
    99== Interoperability of PnetCDF with netCDF-4 == 
     
    1616 
    1717Check the [http://cucis.ece.northwestern.edu/projects/PnetCDF/#InteroperabilityWithNetCDF4 netCDF-4 example programs] in C and Fortran. 
     18 
     19'''Note:''' Currently, using PnetCDF mode is the only way for a netCDF program to perform parallel I/O on files in classic CDF-1 and 2 formats.