[MOAB-dev] error loading exodus files

[Jason Kraftcheck]

On 03/23/2010 06:05 PM, Rajeev Jain wrote:
> Hi,
>
> I'm unable to load/mbsize any .exo file (attached) with the current
> built, it gives on
> error: "NetCDF: Variable not found"
> I'm using NetCDF version 4.0.1 build by Bob in the sharp repos.
> Is there some thing that needs to be defined or missing?
>

The exodus file may be invalid, but the more likely cause is that exodus 
files use a non-standard variant of netcdf.  It is necessary to modify 
some limits in the netcdf library to support files with a large number 
of blocks, sidesets, or nodesets (more than about 500 total.)  See, for 
example, the end of this page: 
http://cubit.sandia.gov/help-version11.1/finite_element_model/export/exporting_exodus2_file.htm

I just wasted quite a bit of time myself today diagnosing such an issue. 
  I think I will add some logic the exodus reader/writer code to check 
for this case and print a more informative error.  Perhaps we should add 
a configure check that prints a warning also.

In the long term, perhaps we should consider re-implementing the exodus 
reader and writer using the NetCDF C API rather than the C++ one.  A 
stock build of ncdump seems to be able to process such files w/out any 
problems.  This leads me to suspect that these limits only affect the 
C++ API in newer versions of NetCDF.  But some further analysis of the 
NetCDF code is probably warranted to verify that before re-implementing 
anything.

- jason