concurrent write access in HDF5

Hi all
i came across this paper :
http://www-fusion-magnetique.cea.fr/tmiaea2009/website/data/fastaux.html?href=docs/000085.ppt
it says that concurrent write access is not supported by HDF5.
Any comments?
thanks
Lana

I took a brief look at your reference.

There are a couple bullets there with the word 'concurrent' in them.
However, its really sketchy for me to determine how that term is being
used in this context.

Is it concurrent writes? Is it concurrent read with write? Is the
concurrency totally independent or coordinated?

For what its worth, I am certain that HDF5 supports concurrent writes
from multiple MPI tasks using the MPI vfds (MPI is used to coordinate
things). I am also certain you can perform totally independent writes to
different HDF5 files and then do some simple tricks with links such that
the collection of files can be treated and viewed by HDF5 applications
as a single, large HDF5 file. So, you get what amounts to a) concurrent
writes and b) a single, large, global file. That sounds basically like
what the bullets describing MDSplus do in the reference.

Mark

···

On Fri, 2010-02-26 at 00:46, lana abadie wrote:

Hi all
i came across this paper
: http://*www-fusion-magnetique.cea.fr/tmiaea2009/website/data/fastaux.html?href=docs/000085.ppt
it says that concurrent write access is not supported by HDF5.
Any comments?
thanks
Lana

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Hdf-forum@hdfgroup.org
http://*mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org

--
Mark C. Miller, Lawrence Livermore National Laboratory
================!!LLNL BUSINESS ONLY!!================
miller86@llnl.gov urgent: miller86@pager.llnl.gov
T:8-6 (925)-423-5901 M/W/Th:7-12,2-7 (530)-753-851

Hi all,

I took a brief look at your reference.

There are a couple bullets there with the word 'concurrent' in them.
However, its really sketchy for me to determine how that term is being
used in this context.

Is it concurrent writes? Is it concurrent read with write? Is the
concurrency totally independent or coordinated?

For what its worth, I am certain that HDF5 supports concurrent writes
from multiple MPI tasks using the MPI vfds (MPI is used to coordinate
things). I am also certain you can perform totally independent writes to
different HDF5 files and then do some simple tricks with links such that
the collection of files can be treated and viewed by HDF5 applications
as a single, large HDF5 file. So, you get what amounts to a) concurrent
writes and b) a single, large, global file. That sounds basically like
what the bullets describing MDSplus do in the reference.

  I took a look through the reference he provides and there's a number of inaccuracies about HDF5 there (which I don't have the time to detail here). I agree with you about the lack of detail about what is meant by concurrent writing, so I'll just provide some additional information to yours about writing with MPI. Multiple-threaded writing is also provided through the HDF5 library being thread safe. Perhaps these two pieces of information will give Lana enough information to go back and get more details about what MDPlus means by concurrent writing.

  Quincey

···

On Feb 26, 2010, at 3:10 AM, Mark Miller wrote:

Mark

On Fri, 2010-02-26 at 00:46, lana abadie wrote:

Hi all
i came across this paper
: http://*www-fusion-magnetique.cea.fr/tmiaea2009/website/data/fastaux.html?href=docs/000085.ppt
it says that concurrent write access is not supported by HDF5.
Any comments?
thanks
Lana

______________________________________________________________________
_______________________________________________
Hdf-forum is for HDF software users discussion.
Hdf-forum@hdfgroup.org
http://*mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org

--
Mark C. Miller, Lawrence Livermore National Laboratory
================!!LLNL BUSINESS ONLY!!================
miller86@llnl.gov urgent: miller86@pager.llnl.gov
T:8-6 (925)-423-5901 M/W/Th:7-12,2-7 (530)-753-851

_______________________________________________
Hdf-forum is for HDF software users discussion.
Hdf-forum@hdfgroup.org
http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org