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Re: Issues with DODS build procedure on Linux/Opteron (fwd)

>To: address@hidden
>cc: Bjarne B?chmann <address@hidden>,
>cc: Peter Gylling J?rgensen <address@hidden>
>From: Karsten Bolding <address@hidden>
>Subject: restoring headers in large netcdf files
>Organization: Bolding & Burchard Hydrodynamics
>Keywords: 200502190949.j1J9ncv2029855 netCDF large file header restore

Hi Karsten,

Way back on 22 Feb, I wrote:

> Then run
> 
>   ncgen -b large.cdl; ls -l large.nc
> 
> For me this took a little over 3 minutes to produce a file over 3 GiB
> in size:
> 
>   -rw-r--r--   1 russ     ustaff   3221225648 Feb 22 16:47 large.nc
> 
> Now this is a CDF1 (classic) netCDF file, so even older versions of
> NCO should be able to handle it, as long as NCO is built with large
> file system support.  If you attempt the NCO operation 
> 
>   ncks -v time large.nc
> 
> I would think it should work, if NCO is built with large file support.
> But I don't have NCO built with large file support to try this with
> right now.  The version I have from 2003 gives what looks like an
> unrelated error:
> 
>   $ /scratch/russ/nco-2.7.1/bin/ncks -v time large.nc time.nc
>   ncks: ERROR unable to determine method for remote retrieval of large.nc
> 
> I will try to build a version of nco with large file support and try
> this out to make sure it works as it should, or if not to report it as
> an nco bug.

Unfortunately, I ran into an NCO build bug that I couldn't find a
workaround for, and it may be a few days before it gets resolved.  An
NCO developer wrote me:

>  ... This is a known problem and I had nailed it on the Opteron and
>  was verifying it and getting the build to work smoothly on my laptop
>  when I realized I no longer had your email.
>
>  I'll try to get it nailed down today, but we just lost the dual
>  Opteron server where most of my code changes were (and weren't
>  committed to CVS yet...).  We have to send it out to get its
>  motherboard replaced - the data's safe, just not available for a few
>  days (I hope).  But I kept notes on my laptop so I should be able to
>  run thru them pretty fast (knock wood).

So I can't yet verify that the current NCO, compiled with large file
support or as a 64-bit executable, will handle a large CDF1 file, but
I still believe it should.  I'll let you know what I find out ...

--Russ

_____________________________________________________________________

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