[Users] Enhancements to Multipole

[Ian Hinder]

On 9 Dec 2010, at 15:54, Frank Loeffler wrote:

> Hi,
> 
> I support all three ideas (but didn't look at the patched yet).
> 
> On Thu, Dec 09, 2010 at 09:43:04AM +0100, Ian Hinder wrote:
>> Two new parameters are introduced: output_ascii (defaults to yes), and output_hdf5 (defaults to no).
> 
> Do you think that most people would actually use the hdf5 version?

I expect that people have very high inertia.  However, on production filesystems, having a large number of output files is frowned upon, and makes things quite slow, so I would encourage people to use HDF5 output whenever possible.

> Could
> it be made the default output if HDF5 is found, disabling ascii in that
> case (unless requested by setting this explicitly by the parameter)?

I think this would be surprising to some people.  Imagine that you were happily using ASCII output in Multipole, and one day decided to include the HDF5 thorn in your thornlist because of something completely unrelated.  The next time you ran, you would find that there was no ASCII output for Multipole, and all your analysis scripts would not be able to deal with the HDF5 data.  I would adhere to the principle of least surprise.

If we want to encourage people to use HDF5 output, we could enable HDF5 by default, but I would not like to disable ASCII by default just yet.  I don't want to enable HDF5 by default just yet, as I don't know what the performance impact of it will be.  Especially on clusters with slow filesystems (I'm looking at you, Kraken).  We could enable it by default after it has seen some more testing.

> That would probably mean that both parameters also accept something like
> "auto" which has exactly that meaning: hdf5 if found, otherwise ascii.


-- 
Ian Hinder
ian.hinder at aei.mpg.de