MPI installand setup - account creation

[Saville]

Hello everyone,

I'm a newbie in terms of setting up a cluster and using MPI. I've got 6
nodes I'm trying to glue together as a cluster. I have a few questions on
some very basic issues:

1) My Master computer is an FC8 machine. One of the nodes in the cluster is
running RH7.3 - does the different in OS present a problem? Will mpirun
programs work (assuming they are built on each machine)?

2) From what I've read, all machines have to have the executable of the
program resident on each machine at the time of running mpirun. And those
programs have to exist in an account of the same username, same
subdirectory:

- Is all that true?
- how identical do those user accounts have to be?
Do they have to have the same group ID, for example?

thanks

[Georg Bisseling]

Post by Saville
Hello everyone,
I'm a newbie in terms of setting up a cluster and using MPI. I've got 6
nodes I'm trying to glue together as a cluster. I have a few questions on
1) My Master computer is an FC8 machine. One of the nodes in the cluster is
running RH7.3 - does the different in OS present a problem? Will mpirun
programs work (assuming they are built on each machine)?
2) From what I've read, all machines have to have the executable of the
program resident on each machine at the time of running mpirun. And those
programs have to exist in an account of the same username, same
- Is all that true?
- how identical do those user accounts have to be?
Do they have to have the same group ID, for example?
thanks

Your questions indicate that you are asking for trouble - no pun intended.
My advice is:
- use the exact same Linux on all boxes that you consider a
cluster. If some nodes are too old to run a newer Linux then
see next item.
- try to have as identical hardware in the nodes as possible.
Having two slow nodes in seven is much worse than just
using the five faster ones. If you are using optimizing
compilers beware to create binaries that work on all nodes
either by creating fat binaries or by restricting too fine
grained optimization.
The worst thing that can happen is one node starting to
swap and the others waiting for it.
- have an NFS server and mount a shared file system on
all nodes. Preferably /home. That nicely solves many
problems. Or do you want each user to edit his/her
.cshrc or .bashrc on all nodes to get the $PATH right?
- have the exact same users on all boxes. Consider to use
NIS to have consistent users and groups or some other
means that is already in use at your site.

If you have no experience in administering a Unix system then do
not start with a cluster.

Good luck!
Georg