"Pascoe, Stephen (STFC,RAL,SSTD)" <stephen.pascoe@xxxxxxxxxx> writes:
> I'd like to clarify how using HDF5 with SZIP support affects the files
> created by the NetCDF4 library.
> Â
> According to the NetCDF4 INSTALL file you can optionally use HDF5+SZIP
> when building NetCDF4. This implies that either SZIP-compressed NetCDF4
> is byte-compatible with ZIP-compressed NetCDF4 or that there are 2
> incompatible compressed NetCDF4 formats (ZIP and SZIP). Can you confirm
> it is the former?
It's simple.
NetCDF-4 cannot create SZIP compressed HDF5 files.
But it is possible to read some HDF5 files with netCDF-4, even though
they were not created with netCDF-4. (This capability will expand with
the 4.1 release, which will read any HDF5 file that does not use
references, circular group structures, or a few other HDF5 features that
are not supported in netCDF).
So the point of building HDF5 with SZIP is to allow these szip
compressed files to be read by netCDF-4. This is a read-only capability.
> Assuming it is the former, what is the advantage of using SZIP? Is SZIP
> automatically used if the HDF5 library has it?
> Â
> Thanks,
> Stephen.
> Â
Fans of szip say it gives better compression.
Thanks,
Ed
--
Ed Hartnett -- ed@xxxxxxxxxxxxxxxx
