Hi Dave,
Point well taken; the final release will contain this information, as well
as some references to the technical explanation. I'll also try to nail
down the extent of the compatibility between superblocks and provide
specific information; if things are not truly forward and backward
compatible, I would like to know. So far, we have not encountered any
issues, however.
-Ward
Ward,
>
> Please add something in the release notes about the latest change to the
> superblock version number. This note should probably go with the first
> release item under 4.4.1-RC1. I suggest something like this:
>
> "Starting with release 4.4.1, new netcdf-4 files will be created with
> superblock version 0 in the underlying HDF5 file format. Netcdf-C versions
> 4.0 through 4.4.0, linked to HDF5 library versions 1.8.x and earlier, were
> created with superblock version 2.
>
> "Superblock versions 0 and 2 appear to be forward and backward compatible
> with old and new library versions. Exact binary compatibility will be
> broken, but data and access should remain the same.
>
> "The combination of netcdf-C library versions from 4.0 to 4.4.1, and HDF5
> library versions 1.10.0 and later, should be avoided. These combinations
> create superblock version 3 files which are not readable with older
> compiled software."
>
> My testing with superblock version 0 files is very limited so far, so I am
> not confident in the above statement "forward and backward compatible". I
> hope that Unidata's testing, and perhaps other netcdf users, can provide
> additional evidence for this claim.
>
> --Dave A.
>
>
> On Mon, Jun 20, 2016 at 2:58 PM, Ward Fisher <wfisher@xxxxxxxx> wrote:
>
>> Hello all,
>>
>> The third (and hopefully final) release candidate for netCDF-C 4.4.1 has
>> been released. As a reminder, the 4.4.1 release will primarily address the
>> issue of backwards-compatible netCDF4 binary files generated on systems
>> using libhdf5 1.10+.
>>
>> Thanks to everybody who provided feedback following the previous release
>> candidate; the bugs that were reported have been fixed. Full release notes
>> may
>> be found here
>> <https://github.com/Unidata/netcdf-c/blob/v4.4.1-rc3/RELEASE_NOTES.md>,
>> but the notable items are listed below.
>>
>> The source tarballs for this release candidate may be downloaded from the
>> Unidata GitHub page, at http://github.com/Unidata/netcdf-c/releases.
>> Documentation may be found at
>> http://www.unidata.ucar.edu/software/netcdf/docs_rc, and the
>> pre-compiled Windows binaries may be downloaded from
>> http://www.unidata.ucar.edu/software/netcdf/docs_rc/winbin.html.
>> Assuming no other issues are reported, we will try to have the full 4.4.1
>> release available in short order.
>>
>> Thanks in advance for any and all feedback; have a great day all!
>>
>> -Ward
>>
>> Ward Fisher
>> wfisher@xxxxxxxx
>> UCAR/Unidata - Software Engineer
>> 4.4.1-RC3 - June 20, 2016
>>
>> - [Bug Fix] Corrected an issue where adding a _FillValue attribute to
>> a variable would result in other attributes being lost. See GitHub
>> #239 <https://github.com/Unidata/netcdf-c/issues/239> for more
>> details.
>> - [Bug Fix][Parallel I/O] Corrected an issue reported by Kent Yang at
>> the HDF group related to Collective Parallel I/O and a potential hang.
>>
>>
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