[Users] CarpetIOHDF5::output_index = "yes" by default?

[Roland Haas]

Hello all,

> Would somebody object to making CarpetIOHDF5::output_index = "yes" the
> default? (It is currently "no".)
>
> It should not hurt to create these small files. (Or, does it?)
It creates files which in itself might be bad. Creating files can be an 
issue on some file systems where creating files is slow (or there might 
be limit on the number of files, that apparently on some clusters 
[admittedly I know of no Cactus users there] can be as low as 1e6 files 
*total*).

Also currently there is a bug/mis-feature in that output_index writes 
indices for both data and checkpoint files. The later probably should 
have a separate switch since index files are less useful there.

If the issue is that we currently have no method for users to create 
index files for existing HDF5 files once eg they find that visualization 
is slow, then for that I have a modified version of hdf5_merge (or was 
it hdf5_extract... anyway one of them) where I simply commented out the 
final H5Dwrite and which generates perfectly fine index files (of the 
"new" format that do not have the extra attribute with just that change 
or "old" ones with the attribute with the obvious changes [that are also 
in]). It's of course a bit of a hack since the tools were not originally 
meant to do that.

Yours,
Roland

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