Re: [netcdfgroup] NetCDF-3 file format changes

Joe,

Do you really need to store more than one large variable in your Netcdf-3 file? Netcdf-3 allows a single fixed or record variable as large as 8 Eib. This is true even in the Netcdf-3 classic format.

I have made large Netcdf-3 classic files like this, with complete satisfaction.

Dave Allured
CU/CIRES Climate Diagnostics Center (CDC)
http://cires.colorado.edu/science/centers/cdc/
NOAA/ESRL/PSD, Climate Analysis Branch (CAB)
http://www.cdc.noaa.gov/

Joe Sirott wrote:
Hi Roy,

There's still a limit on variable sizes with netcdf 3.6 of 4 GB (though not 2GB as I mentioned):

http://www.unidata.ucar.edu/software/netcdf/faq-lfs.html#Large%20File%20Support10

And I'm also guessing (John C: feel free to correct me) that it's 2GB in Java due to the lack of unsigned integers.

Cheers, Joe

Roy Mendelssohn wrote:
Hi Joe:

See http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#Large%20File%20Support0. It has been possible since netcdf3.6

Regards,

-Roy M


On Feb 26, 2008, at 1:11 PM, Joe Sirott wrote:

Hi,

In the "classic" netCDF file format (netCDF-3), a variable without a record dimension cannot be larger than 2GB. This limitation has been giving me a lot of headaches lately. I know that netCDF-4 is supposed to solve this problem, but there are a number of reasons why netCDF-4 is not a good option for me (no Java write support, for one).

I could be missing something, but it seems like a very small change to the netCDF-3 file format would solve this problem. The only requirement would be changing the variable size info in the netCDF header from a 32 bit to a 64 bit int (and, of course, updating the version info in the header).

I'm guessing that I'm not the only netCDF user who has run into this problem and who is also reluctant to move to netCDF-4. Any possibility that Unidata could make these changes?

Cheers,

Joe S.


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NOAA/NMFS
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