MPI: Parallel IO

[ranocha]

We need parallel IO for real 3D applications.

• Tell HDF5.jl to use an MPI-parallel system HDF5 library
  • Documented in Trixi.jl
  • PR for Preferences.jl in HDF5.jl
• Implement a true parallel I/O approach based on parallel HDF5
• Automatically select the best version for parallel I/O: Use true parallel I/O if parallel HDF5 library is found, otherwise continue using the poor man's version of parallel IO we have at the moment
• Document everything
• Add sanity checks if required (use parallel IO if enabled, otherwise send to root)
• Tests for parallel I/O #1486

Please feel free to amend this, @sloede

[sloede]

Thanks, I modified the second point a little bit.

[JoshuaLampert]

Concerning the last point: There exists an issue: JuliaIO/HDF5.jl#1037.

[sloede]

Hej hej, what's the current status on this issue? @JoshuaLampert do you need any assistance? Just asking because I lost tracked...

[JoshuaLampert]

I will finish #1399 once I am back from my holidays (next Monday). There, the parallel reading and writing of the restart files are still missing.

[sloede]

Thanks!

[JoshuaLampert]

Regarding the preferences for HDF5.jl I wait for the developers of HDF5.jl.

[JoshuaLampert]

Most of the boxes in the list can be ticked after #1399 is merged. Maybe add #1486 to the list?

[ranocha]

I did that. Could you please check whether this looks good to you, @JoshuaLampert?

[JoshuaLampert]

LGTM, thanks @ranocha.

[JoshuaLampert]

Now that all of the items are ticked off, the issue can be closed 🎉.

[sloede]

Now that all of the items are ticked off, the issue can be closed 🎉.

Thanks a lot for the great work!