I think there is some way to extend it to at least 4GB-1. IDL claims
that it uses netCDF 3.5, but it supports single variables up to 4GB.
Here is an example:
IDL commands to create a single variable that is almost 4GB and write it
to a netCDF file (write_tomo_volume is a routine I wrote that writes
netCDF files in IDL). An IDL "int" is 16 bits (2 bytes):
IDL> vol = intarr(2000, 1024, 1024)
IDL> write_tomo_volume, 'test.netcdf', vol
Look at the file in the Linux file system:
-rw-r--r-- 1 tomo_user geocars 4194304428 2008-02-26 15:23 test.netcdf
Now read the file back in and check its size:
IDL> vol = read_tomo_volume, 'test.netcdf'
IDL> help, vol
VOL INT = Array[2000, 1024, 1024]
Mark Rivers
> -----Original Message-----
> From: netcdfgroup-bounces@xxxxxxxxxxxxxxxx
> [mailto:netcdfgroup-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Joe Sirott
> Sent: Tuesday, February 26, 2008 3:12 PM
> To: NetCDF Group mailing list (netcdfgroup@xxxxxxxxxxxxxxxx)
> Subject: [netcdfgroup] NetCDF-3 file format changes
>
> 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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