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A Strange Problem in making Parallel (Ansys/CFX 12)

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Old   June 22, 2010, 16:24
Default A Strange Problem in making Parallel (Ansys/CFX 12)
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Ali Sarami
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I have a very strange problem with CFX 12 solver, when I want to use HP MPI local parallel mode of solving.
sometimes all the things are OK and the solver begin to solve. but most of the times after partitionting, when the solver just want to start, suddenly cpu rates fail to zero and nothing happens. no solving, no error, no cpu rate
+--------------------------------------------------------------------+
| Partitioning CPU-Time Requirements |
+--------------------------------------------------------------------+

- Preparations 1.375E+00 seconds
- Low-level mesh partitioning 2.969E-01 seconds
- Global partitioning information 4.688E-02 seconds
- Element and face partitioning information 7.813E-02 seconds
- Vertex partitioning information 1.563E-02 seconds
- Partitioning information compression 0.000E+00 seconds
- Summed CPU-time for mesh partitioning 1.844E+00 seconds

+--------------------------------------------------------------------+
| Job Information |
+--------------------------------------------------------------------+
Host computer: ALI
Job finished: Tue Jun 22 23:36:07 2010
Total CPU time: 2.906E+00 seconds
or: ( 0: 0: 0: 2.906 )
( Days: Hours: Minutes: Seconds )
Total wall clock time: 5.000E+00 seconds
or: ( 0: 0: 0: 5.000 )
( Days: Hours: Minutes: Seconds )

+--------------------------------------------------------------------+
| |
| Solver |
| |
+--------------------------------------------------------------------+

nothing happens after it!!!!!!!

!!!!!! but one thing very strange is that when my computer is connected to internet all the thing is ok and parallel solving proceeds, but when I disconnect it suddenly an error apears and MPI loose its connection!!!!!

why??

a thing to be noted is the fact that in all the above happenings (sometimes solving without error, sometimes errors ,....) I have used the same *.def file!

Please help me with this problem as soon as possible
Thank you
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Old   June 22, 2010, 19:39
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Glenn Horrocks
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This can be caused by a problem in the parallel setup. Do other parallel modes work?
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Old   June 23, 2010, 00:53
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No, unfortunately. none of them works,
for distributed ones the solver is terminated with an error. for local ones the above-mentioned problem happens
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Old   June 23, 2010, 00:59
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but one thing strange is that, sometimes (rarely without any regularity) the parallel solving proceeds while U have used the same parallel settings as the ones that stops!!!
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Old   June 23, 2010, 06:06
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This could be a MPI network error.

I am not too sure about this, so don't nail me down on it, but i do remember that another software i used a few years ago (Folding@Home) had a problem with disconnections in the MPI coupling, when the wireless was trying to reconnect to a network. It was some sort of error in the MPI implementation used on Windows machines.
Do you have a LAN connection active or is the internet protocol the only network protocol activated? It might be that it is just a networking problem.

Also, if you specify more solving partitions then you have CPU's available, it will start to run, but the cpu load drops to zero and nothing happens.
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Old   June 23, 2010, 08:38
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No, I have no LAN,
My CPU has 8 cores and I have just tried to make 2 or 4 of them parallel.
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Old   June 25, 2010, 08:01
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if anyone can help me, I would be the most grateful. I am urgently need your help.
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Old   June 26, 2010, 07:41
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Check that you have licenses available, your network is reliable and your hard drive is not full and you have sufficient memory.
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Old   June 28, 2010, 03:42
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Did you check the size ofthe mesh. I had similar problems when the mesh used was to big to fit in the computer's RAM.

regards,
Jurij
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Old   July 5, 2010, 15:04
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hi ali as sodjaj said it can be result of excess number of mesh check it out.
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Old   July 9, 2010, 01:34
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Hello,

I have the same problem using Win7Pro x64. The solver starts if I choose serial run mode only. The PC has no connection to any network. The firewall is off. ICEM CFD works fine in parallel.

Is there any solution? May be should I install any additional software?
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Old   July 9, 2010, 02:44
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I resolved the issue. The problem is that MPI needs connected LAN with IP address. I just looped one LAN to another LAN on the PC. Then I disabled the LAN and wrote IP number to another LAN. That's it, it works.
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Old   July 14, 2010, 22:45
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i also got the problem for paralel operation
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Old   October 7, 2010, 01:33
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Hi showman

I am having the exact same problem, I couldn't get what you have done. could you please explain me in details?

Thanks
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