How to store and retrieve file access properties?

Hallo,

I write a dataset with optimized (to the size of the data) file access
properties to an HDF file. Than I close the dataset and file.
I would like to be able to open the file with the same access
properties. However, I do not know in advance the size of the dataset
in the hdf file to determine the access properties in advance.

Is there a way to reset access properties on an open file?

Thanks
Eryk

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Witold Eryk Wolski

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Hi Eryk,

Hallo,

I write a dataset with optimized (to the size of the data) file access
properties to an HDF file. Than I close the dataset and file.
I would like to be able to open the file with the same access
properties. However, I do not know in advance the size of the dataset
in the hdf file to determine the access properties in advance.

  You can get a copy of the access property list for files and datasets before you close the objects. However, this won't help if you are restarting the application (or using another one). Perhaps having some way to serialize/deserialize property lists would be useful?

Is there a way to reset access properties on an open file?

  Not currently, no.

  Quincey

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On Sep 17, 2010, at 11:01 AM, W Eryk Wolski wrote:

I think that could be useful in general.

But, in particular, for file access properties, many of those effect the
fundamental 'boot' process in opening a file to begin with. So, unless
you had a way to, for example, encode them into the boot block or
'user-defined' segment, or a way to somehow read them from a file
without having to really 'open' it, I am not sure it would help there.

This is related to my experiences writing my own VFD but having
difficulty getting HDF5 library to automatically detect and use the
desired VFD when re-opening a file.

Mark

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On Fri, 2010-09-17 at 02:53, Quincey Koziol wrote:

  You can get a copy of the access property list for files and datasets
before you close the objects. However, this won't help if you are
restarting the application (or using another one). Perhaps having
some way to serialize/deserialize property lists would be useful?

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Mark C. Miller, Lawrence Livermore National Laboratory
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