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Re: 20010808: netCDF on T3E

>To: address@hidden (netCDF support)
>From: "Daniel S. Schaffer" <address@hidden>
>Subject: netCDF on T3E
>Organization: NOAA/FSL
>Keywords: 200108081441.f78Ef3125942

Hi Dan,

> My colleague Tom Henderson and I have been in contact
> with Russell.  I recently have run into a problems with
> netCDF on a T3E.  I am executing the following code within
> an MPI program:
> 
>       status=nf_open ('cgoa_grid_2.nc',nf_nowrite,ncid)
>       print *, 'got to 2'
>       status=nf_inq_att (ncid,nf_global,'type',attype,ltype)
>       print *, 'called nf_inq_att ', ncid, attype, ltype, status
> 
> 
> While I have not yet been able to isolate the problem completely,
> I get one of two behaviors depending on the rest of the code.
> Either I get:
> NC_SHARE not implemented for ffio
> in the call to nf_open

First, is it possible you have not included the "netcdf.inc" include
file in this subroutine, so the parameters "nf_nowrite" and
"nf_global" are not initialized?  That would explain the symptoms.

Also looking at the src for libsrc/ffio.c, it appears as if the message

 NC_SHARE not implemented for ffio

will only be printed if the "nf_share" mode bit has been set on open,
but since you are opening with "nf_nowrite" mode, that doesn't seem to
make sense.  The "nf_nowrite" parameter is initialized in the
netcdf.inc file as 0, whereas "nf_share" is initialized to be 2048.
Does another thread also open the file and set the "nf_share" flag
first?  If so, I don't think that will work; for the T3E parallel
netCDF used from multiple threads, you should instead be using the
"underbar underbar" functions like nc__open().  See the Fortran netcdf
man page for descriptions of these, which were explicitly added for
the T3E.

> or I get status -49 in the call to nf_inq_att
> 
> Any ideas what might be going on here?

The status -49 for the Fortran interface is defined in the netcdf.inc
include file:

      parameter (nf_enotvar = -49)

which means "Variable not found" if you use the nf_strerror() to
convert it to an error message.  The variable id you supply,
"nf_global", is the ID of the global pseudo-variable and as a parameter
is assigned the value 0 in the netcdf.inc include file.  This should
always be "found".  Is it possible you have not included the
netcdf.inc file in this subroutine, so nf_global is uninitialized?

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu