Felix,
H5Dcreate is a collective call. ALL processes have to participate in creation
of each dataset. After datasets are created, data can be written independently
by each process to a corresponding dataset.
Elena
On Feb 27, 2010, at 4:00 PM, Felix Schmitt wrote:
> Hello,
>
> I am quite new to HDF5 so this might probably be a beginners question:
> I want to create and access different datasets depending on my mpi rank.
> Accessing parts of one dataset via hyperslabs works perfect, but the
> following doesn't work:
> I want to write the name of each processor in a different dataset which is
> named 'attr_processor_[mpi_rank]'. However, it will only create one dataset
> named 'attr_processor_0'.
>
> plist_id = H5Pcreate(H5P_FILE_ACCESS);
> H5Pset_fapl_mpio(plist_id, mpi_comm, MPI_INFO_NULL);
>
> file_id = H5Fcreate("test.h5", H5F_ACC_TRUNC, H5P_DEFAULT,
> plist_id);
> H5Pclose(plist_id);
>
> ... // some hsize_t initializations and so on
>
> hid_t procs_dataset_id;
> hid_t proc_name_t;
> // datatype for processor name
> proc_name_t = H5Tcopy(H5T_C_S1);
> H5Tset_size(proc_name_t, MPI_MAX_PROCESSOR_NAME + 1);
>
> plist_id = H5Pcreate(H5P_DATASET_XFER);
> H5Pset_dxpl_mpio(plist_id, H5FD_MPIO_INDEPENDENT);
>
> // create dataset
> char *proc_dataset_name = new char[256];
> hid_t proc_dataset_space = H5Screate(H5S_SCALAR);
>
> memset(proc_dataset_name, 0, 256);
> sprintf(proc_dataset_name, "%s_%d", "attr_processor", mpi_rank);
> procs_dataset_id = H5Dcreate(group_id, proc_dataset_name, proc_name_t,
> proc_dataset_space, H5P_DEFAULT);
>
> // retrieve mpi processor name
> char *proc_name = new char[MPI_MAX_PROCESSOR_NAME + 1];
> int result_len = 0;
> MPI_Get_processor_name(proc_name, &result_len);
> proc_name[result_len] = 0;
>
> // write processor name
> H5Dwrite(procs_dataset_id, proc_name_t, proc_dataset_space,
> proc_dataset_space, plist_id, proc_name);
>
> // cleanup
> H5Dclose(procs_dataset_id);
> H5Sclose(proc_dataset_space);
> H5Pclose(plist_id);
> delete[] proc_dataset_name;
> delete[] proc_name;
>
> ... // writing the actual data
>
> Thanks for replying.
> Felix
>
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