[Paraview] [EXTERNAL] parallel readers?

[Anton Shterenlikht]

	From wascott at sandia.gov Mon Mar 25 18:09:34 2013

	Anton,
	I believe it depends somewhat on the reader, but your basic understanding is correct.  I know of three types of readers 1) those that have not been parallelized, 2) those that run in parallel, but will not spread an individual file among multiple servers (such as Exodus and Spyplot) (read in parallel, processing in parallel), and 3) readers that will spread a single file among multiple servers (raw binary reader) (I am not sure on the read, processing in parallel).

	Alan

Alan,

it's exactly the phrase "spread an individual file"
that gets me confused. For me what you wrote means
that I must have a single (possibly huge) datafile.
A parallel reader will then presumably open multiple
processes which will read different chunks of the same
file into paraview.
If that's the case, then that's easy for me (the user).
I just prepare my single datafile and let the reader do
all the work.

In my case the most suitable reader is ImageReader,
which, according to this page, "truly" works in parallel:
http://paraview.org/Wiki/ParaView:FAQ#Which_readers.2Ffilters_work_in_parallel_.3F

However, making a single datafile is a lot more
costly for me than making say 4096 individual files,
one from each compute process. The difference can be
in the order of 30-60 min. What I want from a parallel
reader is that it would be coordinating reading all these
separate files into paraview, with me providing instructions
on how to assemble the global dataset from multiple
read pieces of data. Is that model supported at all
by paraview readers, and by ImageReader in particular?

Thanks

Anton


	-----Original Message-----
	From: paraview-bounces at paraview.org [mailto:paraview-bounces at paraview.org] On Behalf Of Anton Shterenlikht
	Sent: Monday, March 25, 2013 8:48 AM
	To: paraview at paraview.org
	Subject: [EXTERNAL] [Paraview] parallel readers?

	What is meant by a parallel reader?
	If I have n raw binary files, all forming parts of one global model, then can I reade all of them in paraview in parallel if I have n processes?

	Thanks

	Anton
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