writing large variables

[Rob Latham]

On Tue, Jan 15, 2013 at 05:09:05PM -0700, John Clyne wrote:
> Is it possible to write a large variable (>4GB) to a file with pnetcdf and read back the variable from the resulting file with netCDF? Outputting a large variable with pnetcdf appears to require passing the NC_64BIT_DATA flag (not NC_64BIT_OFFSET) to nc_create_par() - without this flag an error is generated. The file is written successfully, but when NC_64BIT_DATA is used the file is unrecognized by netcdf. For example:
> 
> yslogin2[43] ncdump -h vx.0000.nc0
> ncdump: vx.0000.nc0: NetCDF: Unknown file format
> 
> From what I can gather from the web the NC_64BIT_DATA results in the generation of a CDF-5 formatted file. Is there support for CDF-5 in netCDF, or any other options for mixing pnetcdf and netCDF?

Hi John:  the short answer is there is no "unidata netCDF" support for
pnetcdf's CDF-5 (giant variables) file format.  

I've been working with Unidata  on and off over the last few years to
find a way that we could use NetCDF-4's "netcdf on pnetcdf" feature to
support CDF-5, but that support right now only exists as a series of
patches yet to be incorporated into Unidata's tree.

==rob

-- 
Rob Latham
Mathematics and Computer Science Division
Argonne National Lab, IL USA