Using several nodes in a simulation (OpenFOAM)
Dear all,
I'm quite new in using OpenFOAM in a cluster, using only one node is a breeze... the problem starts when I need to use more than one node... I'm using the command 'mpirun --host node1,node2 -np 48 rhoSimpleFoam -parallel' and I get the following info/error There are not enough slots available in the system to satisfy the 48 slots that were requested by the application: rhoSimpleFoam Either request fewer slots for your application, or make more slots available for use. A "slot" is the Open MPI term for an allocatable unit where we can launch a process. The number of slots available are defined by the environment in which Open MPI processes are run: 1. Hostfile, via "slots=N" clauses (N defaults to number of processor cores if not provided) 2. The --host command line parameter, via a ":N" suffix on the hostname (N defaults to 1 if not provided) 3. Resource manager (e.g., SLURM, PBS/Torque, LSF, etc.) 4. If none of a hostfile, the --host command line parameter, or an RM is present, Open MPI defaults to the number of processor cores In all the above cases, if you want Open MPI to default to the number of hardware threads instead of the number of processor cores, use the --use-hwthread-cpus option. Alternatively, you can use the --oversubscribe option to ignore the number of available slots when deciding the number of processes to launch. I'm doing something wrong, please help... OpenFOAM - v1906 |
Did you find what was going wrong?
I am trying to simulate in a cluster but I dont have idea how to start |
This had nothing to with OF.
I strongly suggest not to rush running big cases in a supercomputer to avoid wasting money (of taxpayers). Learn 5w1h of the cluster, follow the tutorials, start with the simplest case, and build up from there. |
Hello Didu,
As HPE said, your problem is not related to OpenFOAM but to openmpi. It would be useful to know which openmpi version you are using. I think you just need to specify how many processes you want to run on each node. Try using this syntax: Code:
mpirun --host node1:24,node2:24 -np 48 rhoSimpleFoam -parallel Cheers, Yann |
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