I was writing some netCDF tests for parallel I/O, trying to write an array of strings with parallel I/O.
But I get this error:
HDF5-DIAG: Error detected in HDF5 (1.10.1) MPI-process 2: #000: H5Dio.c line 269 in H5Dwrite(): can’t prepare for writing data
major: Dataset
minor: Write failed #001: H5Dio.c line 345 in H5D__pre_write(): can’t write data
major: Dataset
minor: Write failed #002: H5Dio.c line 656 in H5D__write(): Parallel IO does not support writing VL datatypes yet
major: Dataset
minor: Feature is unsupported
This suprised me. Will VLEN ever be supported with parallel I/O?
Is this just a restriction on writing? Can I read VLENs with parallel I/O?
Yes, this is a known limitation of the parallel HDF5 implementation. Enabling support for VL types is on our to-do list, but there is no time estimate when it will be available.
No change. The current (internal) VL representation is rather inefficient and parallelization would probably make sense only after that’d been fixed/revised. G.