In defense of the HDF team, this is difficult capability to enable in
practice. This is because prior to compression you don't know how much
space a given write will require, so parallelizing writes (especially
if they aren't performed collectively) is not straightforward and
requires a significant amount of coordination.
Rob
On Feb 13, 2008, at 12:07 PM, Ed Hartnett wrote:
Thomas Green <thomas.green@xxxxxxxxxxxxxxxx> writes:
NetCDF users,
Just a quick question. Can NetCDF4 use MPI-IO if also using
compression? I read on the HDFgroup website that MPI-IO and
compression
are not compatible but I am not sure if this still applies and how it
affects NetCDF4.
The HDFgroup FAQ related to MPI-IO and compression:
http://www.hdfgroup.com/hdf5-quest.html#p5comp
Many thanks,
Tom
No, sorry, that is not allowed by HDF5.
If you want parallel I/O you must use uncompressed data.
I have asked the HDF5 team whether this might be changed in a future
HDF5 release...
Ed
--
Ed Hartnett -- ed@xxxxxxxxxxxxxxxx
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