Hello,
> I used "ncrcat" to creat a very large netcdf file(a combination of 25 years'
> 17 level zonal wind field). Now when I used "addfile" command to use this
> file. there will be an error message" File requested does not exit". Is this
> due to the file size limit of NCL? Thank you very much.
Regarding "ncrcat," please be aware that it's part of the netCDF Operators
(NCO) software (http://nco.sourceforge.net/). The NCO is not part of NCL,
though both work with the netCDF file format.
When you state that you "...create a very large netcdf file" -- just how
large is "very large?" If you create a file that is larger than 2 GB,
then you've exceeded the file size supportable by typical Unix/Linux file
systems, and thus also supportable by the NCO and NCL. This is due to the
32-bit hardware on which most folks work: only files of size 2^31 or
smaller are addressable.
You can perform operations on files that are larger in size than 2 GB by
building into your netCDF library support for large files. Please see:
netCDF and large file support
http://www.unidata.ucar.edu/packages/netcdf/faq.html#lfs
http://www.unidata.ucar.edu/packages/netcdf/f90/Documentation/f90-html-docs/guide9.html#2236524
for information about large file support, and
http://www.unidata.ucar.edu/packages/netcdf/INSTALL.html
for information about how to install netCDF libraries built with large
file support.
NCO and large file support
http://sourceforge.net/forum/forum.php?thread_id=803589&forum_id=9830
Note that, for the NCO and NCL to work with files greater than 2 GB in
size, you must have an appropriate netCDF installation. For all of this
to work, you'll need 64-bit hardware and an operating system that supports
such hardware.
I would suggest that you first determine if your netCDF library is built
to support large files. Following that, make sure that the NCO are built
using the netCDF libraries that support large files. Lastly, for NCL to
operate on your file, you'll need a version of NCL built with large file
support. Again, all of this will require the appropriate hardware and
operating system.
If you would, could you pass along the bit of NCL code you're using to
read this file, and the exact wording of the error message(s) you're
seeing?
If it's possible, could we obtain a copy of your very large file, so that
it can be used for testing of NCL with large file support?
-Rick.
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