[MITgcm-devel] [Fwd: netCDF 3.6.0-beta6 with Large File Support]

[Ed Hill]

Hi folks,

We've already had one user hit the 2GB file size limit with MITgcm/mnc,
so the following looks like a real step forward for netCDF 3.x.

I'll build and announce new netCDF 3.6.0-beta RPMs asap.

Ed

-----Forwarded Message-----
> From: Russ Rew <russ at unidata.ucar.edu>
> To: netcdfgroup at unidata.ucar.edu
> Subject: netCDF 3.6.0-beta6 with Large File Support
> Date: Thu, 14 Oct 2004 10:23:43 -0600
> 
> Hi,
> 
> A new beta release of netCDF-3.6.0 is available for external testing:
> 
>   ftp://ftp.unidata.ucar.edu/pub/netcdf/netcdf-beta.tar.gz
> 
> Simplified installation instructions for the beta release are
> available from:
> 
>   http://www.unidata.ucar.edu/packages/netcdf/INSTALL-beta/
> 
> Although we have tested this release extensively and believe it is a
> candidate for final release, we would appreciate feedback on any
> problems you might discover.
> 
> NetCDF version 3.6 improves large file support, Windows compatibility,
> ease of installation, and performance using the Fortran-90 interface.
> In addition, it fixes a few bugs.
> 
> In previous releases it was possible to create netCDF files that
> exceeded 2 GiB by observing fairly severe constraints on the structure
> of the data.  For example, you could use a very large fixed-size
> variable as the last variable, or you could use the record dimension
> for large variables and use a large number of records.  Such
> restrictions were necessary due to the use of 32-bit fields in the
> netCDF format for offsets pointing to the beginning of data for each
> variable.
> 
> Version 3.6 introduces a new variant of the netCDF file format, while
> preserving backward compatibility with the existing format.  The new
> variant has 64-bit fields for file offsets, removing many of the size
> constraints for netCDF files.  Greg Sjaardema of Sandia Labs
> contributed C library code to support 64-bit offsets, and we added
> changes to increase the maximum variable and record size, to permit
> use from Fortran, C++, and Java interfaces, to support creation of
> large files with the ncgen utility, and to check declared variable
> shapes for conformance with remaining size constraints.  The new
> library will access data transparently in both the classic and 64-bit
> offset formats.
> 
> Version 3.6 is configured to use Large File Support by default if
> available on the target platform.  Building and installing from source
> has been simplified so that there is no need to set environment
> variables on most platforms.
> 
> We are maintaining a list of questions and answers for netCDF large
> file support:
> 
>   http://www.unidata.ucar.edu/packages/netcdf/faq-lfs.html
> 
> More information about the 3.6.0-beta release is contained in the
> RELEASE_NOTES: 
> 
>   http://www.unidata.ucar.edu/packages/netcdf/release-notes-3.6.0-beta6
> 
> or the new draft documentation:
> 
>   http://www.unidata.ucar.edu/packages/netcdf/docs/netcdf/index.html
> 
> If you have other questions or encounter problems with the beta
> release, please contact support at unidata.ucar.edu.  Thanks!
> 
> -- Russ Rew
> -- Ed Hartnett
-- 
Edward H. Hill III, PhD
office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
             Cambridge, MA 02139-4307
emails:  eh3 at mit.edu                ed at eh3.com
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