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The = I/O is only parallelized for writing of XDA/XDR files at present. = It is blocked, and it is performed processor-wise. So you can = write a serialized mesh file from a parallel, distributed mesh. = For all other mesh types the mesh is serialized to all processors, and = processor 0 performs the write.
The intent is to extend the = parallel I/O functionality to any/all formats which support it. = Thus, parallel ExodusII I/O should be pretty high on our list.
= Can you generate a 3D exodusII mesh, preferably hybrid element, in = serial and distributed format? Preferably, 1, 2, 4, 8 processor = distributions.
-----Original = Message-----
From: Derek Gaston [mailto:firstname.lastname@example.org]
= Sent: Mon 6/23/2008 5:15 PM
To: email@example.com= urceforge.net; Kirk, Benjamin (JSC-EG)
Subject: Using Parallel = Mesh
What do I need to do to actually use = ParallelMesh with parallel I/O?
So far I've done --enable-parmesh = and used delete_nonlocal_elements
(after doing a build_cube)... then = I've computed a solution and
written a single exodus file. In = writing that Exodus file is it
serializing the mesh first? Or = is it doing that block chunked I/O
that Ben put into the code? = Somehow it's getting all of the elements
into that Exodus = file....
Here's what I'm thinking I'd like to do: Let's say I = have a coarse
mesh in exodus format (all in one file) to start = with. I want to read
this in (preferably in parallel, even if = that means I need to do an
offline filetype conversion first) then = uniformly refine it to
saturate all available memory... compute a = solution... then write it
out (hopefully a parallel write... but = doesn't have to be).
Is that doable now?
Also, how = much work do you think it would be to be able to read (and
write) = decomposed Exodus files? The writing part sounds especially
= easy (I believe that decomposed Exodus files are just regular exodus
The idea is that I'm going to be running a simulation = that uses
approximately 40 million elements on about 1,000 = procs. What I do
doesn't have to be pretty... it just needs to = work. If the mesh I run
on is just a cube... so be it... if it = looks like a cylinder that
would be a huge bonus. I am open to = all ideas.