[hdf-forum] HDF5 chunking mechanism

[Francesc Alted]

A Monday 15 June 2009 16:50:44 Mark Howison escrigué:
> Hi Francesc,
>
> I'm detecting the 256 writes using POSIX traces from a performance
> profiling tool called IPM that we use at NERSC:
>
> http://www.nersc.gov/nusers/systems/franklin/tools.php#ipm
>
> I attached the C code I am using, but it uses H5Part, a veneer API we
> have built on top of HDF5. I'll try to breakdown the H5Part calls in
> terms of their corresponding HDF5 functionality:
>
> H5PartOpenFileParallelAlign - opens the file with the MPI-POSIX VFD
> and sets the alignment to 1MB using the H5Pset_alignment function
>
> H5PartSetStep - creates an HDF5 group called "/Step#N"
>
> H5BlockDefine3DChunk - stores the chunk dimensions in an H5Part data
> structure
>
> H5BlockDefine3DLayout - creates HDF5 dataspaces
>
> H5BlockWriteFieldFloat32 - creates a group off of "/Step#N" and a 3D
> dataset, with the chunk dimensions in a creation property list, then
> calls H5Write using the defined dataspaces

Ok.  But an auto-contained file that does the same thing, but using the plain 
HDF5 C-API would be far easier for us to look at.  Could you provide this 
please?

-- 
Francesc Alted

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