[netcdfgroup] HDF5 1.10.1 solves network file problem on Mac OS

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: [netcdfgroup] HDF5 1.10.1 solves network file problem on Mac OS
• From: Dave Allured - NOAA Affiliate <dave.allured@xxxxxxxx>
• Date: Thu, 20 Apr 2017 15:27:23 -0600

Here is a positive test result for HDF5 release 1.10.1-pre2.  Reminder,
HDF5 is the underlying format for all netcdf-4 files.

With HDF5 1.10.0 (and patch1) on Mac OS, all access to NFSv3-mounted files
would fail due to the previously reported flock problem.  In plainer terms,
HDF5 1.10.0 was not able to read or write any HDF5 or netcdf-4 files on
network file servers.  This was due to a deficiency in NFSv3 support for
Mac OS.

This problem was solved in 1.10.1 pre-releases.  HDF5 support added a fix
that disabled file locking behavior, thus avoiding the problem.  Please see
details in the release notes starting with 1.10.1-pre2, under "Other New
Features".

https://gamma.hdfgroup.org/ftp/pub/outgoing/hdf5/hdf5-1.10.1-pre2-RELEASE.txt

The fix is not a build fix, rather it is a run time environment variable
setting.  This is versatile.  File locking can be used with local files,
and disabled only when necessary to access network files.

Thanks to the HDF5 Group for providing the flock fix.  This will allow my
work group and other Mac users to advance past HDF5 1.8 for netcdf-4
access.  I look forward to the final release of HDF5 version 1.10.1, which
is still a few weeks away.

--Dave Allured
NOAA/OAR/ESRL/PSD/CIRES