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From: Murat Knecht (MKNECHT_at_[hidden])
Date: 2007-08-30 11:51:19


Hi,
I have a question regarding the --host(file) option of mpirun. Whenever I
try to fork a process on another node using Spawn(), I get the following
message:

Verify that you have mapped the allocated resources properly using the
--host specification.

I understand this can be fixed by providing the hostnames which will be
used either by --host or by using a hostfile containing the names and
possibly the slots available.
This may be an acceptable solution, if one wants to start the same process
on several blades, but what about starting a parent process which then
initiates different child processes on other blades?
In this scenario mpirun initially does not need the information of which
other blades exist, but is only supposed to start the parent process
locally. Surely, there must be a way not to previously specify blades, but
to load this information at runtime, especially in a changing landscape
where nodes are added at runtime.
Is there a way to avoid this --host option?

I'm using the latest version of OpenMPI (1.2.3).

Best regards,
Murat