Re: question about HDF5 parallel use of unlimited dimensions...

• To: netcdf-hdf@xxxxxxxxxxxxxxxx
• Subject: Re: question about HDF5 parallel use of unlimited dimensions...
• From: "Muqun (Kent) Yang" <ymuqun@xxxxxxxxxxxxx>
• Date: Thu, 30 Jun 2005 08:03:19 -0500 (CDT)

Ed:
On Wed, 29 Jun 2005, Ed Hartnett wrote:

> Howdy all!
> 
> I have a question about parallel programming with HDF5. Do parallel
> programmers just not use unlimited dimensions?
> 
You can use unlimited dimensions for parallel programming.
> I noticed that H5Dextend is a collective operation. This would make it
> difficult for programs to add a record at a time.
> 

I don't think it is difficult as long as all processors participate.

I may miss something. Parallel NetCDF tests I wrote include unlimited 
dimension dataset tests for both collective and independent modes. Tests 
passed.

Although H5Dextend is collective, I remember that I noticed that doesn't 
matter for netCDF4 users. I may be wrong. Maybe other people can give 
some insights.

Kent

 > Alternatively I could imagine a scheme where extending the 
dataset > would be buffered - some large number of records could be added
> whenever the current batch is used up.
> 
> Any thoughts or comments about the use or misuse of unlimited
> dimensions with HDF5 parallel would be most welcome.
> 
> Thanks!
> 
> Ed
> 
> 

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