Re: [ferret_users] Ferret & > 2Gb netcdf files

[Glenn Carver <Glenn.Carver@xxxxxxxxxxxxxxxx>]

Hi Jimmy,

It is possible to create netcdf files > 2Gb using the classic netcdf 
interface. See 
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf/Large-File-Support.html 
for more details.  I guess you're doing it this way?

However, this still uses the 32bit offset but I specifically want to 
change the netcdf mode to 64bit which you do by passing a flag to 
NC_CREATE. This changes the magic number at the start of the file 
which may break netcdf savvy software if it's linked against older 
versions of the netcdf library.

This assumes of course your OS support large files.

  Glenn



At 6:05 pm -0600 3/11/06, jimmyc@iastate.edu wrote:
> Hi All-
> I have been using ferret to display WRF output at 64 bit, >2GB files 
> now for some time. Is ferret handling them correctly? Or is it that 
> certain features in NetCDF do not function but one can still use the 
> data?
>
> jimmyc
>
> On Fri, 3 Nov 2006, Ansley Manke wrote:
>
> > Hi Glenn,
> > Ferret gets its netCDF libraries through the OPeNDAP libraries, 
> > which at this time don't support all of the capabilities of the 
> > Unidata netCDF Version 3.6.0 (which is able to support the file 
> > format with 64-bit offsets for very large files).
> >
> > The OPeNDAP folks are working on this now, and I hope it won't be 
> > too much longer before we'll be able to offer this in Ferret as 
> > well.
> >
> > Ansley
> >
> >
> > Glenn Carver wrote:
> > > I'm doing some high resolution modelling which is resulting in 
> > > problems with the file sizes and I may need to generate netcdf 
> > > files > 2Gb by enabling '64bit offset' mode when creating netcdf 
> > > output files from the model.
> > >
> > > I was wondering whether the 64bit offset netcdf files are handled 
> > > by Ferret? (obviously I haven't tried it 8-).  I had a read of the 
> > > manual and tried a google but couldn't find the answer?  I note 
> > > there's a 64bit linux ferret binary but does it understand 64bit 
> > > netcdf files?  Are there other 64bit binaries?
> > >
> > > Thanks,
> > >           Glenn
> --
> James Correia Jr.
> Ph.D. Candidate in Agricultural Meteorology
> Former President: ISU Graduate Meteorology Club
> Dept. of Agronomy, Iowa State University
> *********************************************
> Email: jimmyc@iastate.edu
> Phone: 515-294-9870
> Web: http://bruce.agron.iastate.edu/jimmyc/
> ISU GMC: http://www.stuorg.iastate.edu/gmc/
> *********************************************
> "There is a difference between knowing the path and walking the path"
> -"Morpheus"
>
> "Wisdom. Strength. Courage. Generosity. Each of us are born with one of
> these. We must find the other three inside of us."
> from "Into the West"