The HDF5 features that netCDF-4 does not support do not occur very often in
the wild. The vast majority of existing HDF5 files should be read by
netCDF-4 without problems.
The main difference is that HDF5 can have circular group structure, and
netCDF-4 does not accept that. There is an archaic date format in HDF5
which is not supported by netCDF-4. NetCDF-4 does not permit the writing of
szipped files (HDF5 does), but netCDF-4 can read szipped files.
I can't remember any other differences. Ward and Dennis, did I miss
something? Or has something changed?
Ed
On Fri, Apr 22, 2016 at 12:33 PM, Pedro Vicente <
pedro.vicente@xxxxxxxxxxxxxxxxxx> wrote:
>
> Hi Russ
>
> >>>However, there are HDF5 files that netCDF-4 will not open and read, by
> design. See the answer to the FAQ How can I convert HDF5 files into
> netCDF-4 files?, which lists some HDF5 features netCDF-4
> *>>>>intentionally *does not support
>
> yes !
>
> that was my impression debugging the code some years ago, netCDF was *
> intentionally * returning a failure on a pure HDF5 file
> glad you pointed that document, I had missed that
>
> ----------------------
> Pedro Vicente
> pedro.vicente@xxxxxxxxxxxxxxxxxx
> https://twitter.com/_pedro__vicente
> http://www.space-research.org/
>
>
>
> ----- Original Message -----
> *From:* Russ Rew <russrew@xxxxxxxxx>
> *To:* Ed Hartnett <edwardjameshartnett@xxxxxxxxx>
> *Cc:* John Shalf <jshalf@xxxxxxx> ; cf-metadata@xxxxxxxxxxxx ; Discussion
> forum for the NeXus data format <nexus@xxxxxxxxxxxxxxx> ; HDF Users
> Discussion List <hdf-forum@xxxxxxxxxxxxxxxxxx> ; Richard.E.Ullman@xxxxxxxx
> ; Marinelli, Daniel J. (GSFC-5810) <daniel.j.marinelli@xxxxxxxx> ;
> dmh@xxxxxxxx ; netcdfgroup@xxxxxxxxxxxxxxxx ; Miller, Mark C.
> <miller86@xxxxxxxx>
> *Sent:* Friday, April 22, 2016 11:12 AM
> *Subject:* Re: [Nexus] [netcdfgroup] [Hdf-forum] Detecting netCDF versus
> HDF5 -- PROPOSED SOLUTIONS --REQUEST FOR COMMENTS
>
> On Thu, Apr 21, 2016 at 1:56 PM, Ed Hartnett <
> edwardjameshartnett@xxxxxxxxx> wrote:
> ...
>
>> The ability of netCDF-4 to open HDF5 files which were written by HDF5 is
>> an important feature. It means that users can use tools that were written
>> for netCDF on their existing HDF5 files.
>>
>
> However, there are HDF5 files that netCDF-4 will not open and read, by
> design. See the answer to the FAQ How can I convert HDF5 files into
> netCDF-4 files?
> <http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#How-can-I-convert-HDF5-files-into-netCDF-4-files>,
> which lists some HDF5 features netCDF-4 *intentionally *does not support,
> primarily because these specific features seemed to be of dubious utility
> for little benefit.
>
> NetCDF-4 supports a simpler data model than HDF5, and that was meant to be
> a feature, not a bug.
>
> --Russ
>
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