[Nek5000-users] MPI-IO in Nek

[nek5000-users at lists.mcs.anl.gov]

Also, I asked this specifically because my largest job using 8192 tasks was
killed at the first IO-time due to being out of memory although I was using
the .f000 format (either when every processor was outputting or 64 of them)
. Any ideas as to why that might have happened? 

 

Hesam

 

From: nek5000-users-bounces at lists.mcs.anl.gov
[mailto:nek5000-users-bounces at lists.mcs.anl.gov] On Behalf Of
nek5000-users at lists.mcs.anl.gov
Sent: Saturday, October 19, 2013 12:18 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] MPI-IO in Nek

 

Hi Neks

 

After reading the following post, the inherent differences b/w .fld and
.f000 files became somehow clear to me. However, I have a few questions: 

 

https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2013-June/002147.html

 

1)      Is this correct that compiling with MPI-IO only requires adding this
flag in makenek:  PPLIST="MPIIO" ? or is there anything else I need to do?

2)      I noticed that if you do not add the above flag but set param(66)
and param(67) in usrdat2 to 6 or -6 ,  it does generate .f000 files. I
assume it implicitly used MPIIO, right?

3)      If I use several directories for outputting multiple files (by say
setting p65=-64 in the .rea file), how can I restart from those multiple
files associated with a single checkpoint in the *.rea* file? 

 

Thanks a lot for your help

 

Best,

Hesam

 

 

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